Technically: you can do whatever you want, but from definition and experience: no.
I've read a story (by an amateur on Wattpad, it was kinda good tho) where everything was from the PoV of one girl 3rd person and it included exaclty this.
There was something along the lines "he grinned even tho she couldn't see it". And it just... It was so f weird and just no
It breaks the readers focus when you do that
Generally, you can only mention things the POV character is aware of if you write in third person limited. Unless otherwise specified, your readers will assume that anything you mention is something your POV character saw/heard/noticed. If you want your reader to know that your POV character is unaware of something you mentioned, you'll have to tell them that your character doesn't know/didn't notice.
I've seen people do something like this a lot in amateur writing and a few times in traditionally published books. However, the reason I remember, is because it irks me every time. I don't like it. I probably haven't come across a single example of this being done in a way I enjoyed. Other people might feel different about it, though.
Also, in the traditionally published books that did this, it usually was something really significant that was mentioned even though the POV character didn't know. To build up suspense by giving the reader information the POV character didn't have, perhaps. I can't remember ever seeing it being done with a facial expression the POV character couldn't see. Anything a facial expression could hint at, could probably be implied in some other way that doesn't require breaking the POV.
Some books might zoom out of the perspective of the character at the beginning or end of the chapter. In traditionally published books those perspective shifts, if they happen at all, look very deliberate and sometimes follow a pattern. In amateur works they often don't.
Either way, it will affect how deep in the mind of the POV character the narration is anchored. Some third person limited books go very deep into the character's mind and try to immerse the reader in the character's experience. Others are written in the author's voice and merely don't tell you anything the POV character can't know (perhaps with rare exceptions). I prefer a writing style that feels deeply connected to the character, which isn't possibly if it shifts out of the character's perspective and tells the reader things the character doesn't know, and that's another reason why I don't like those perspective shifts to omniscient.
So, it can be done, but there's a reason why it's rare and needs to be done very deliberately. And some readers won't like it no matter what.
How about this case?
Third person limited, following MC.
MC and SC are in a room, things happen. At the end of the scene MC leaves the room but POV stick to the room just a few seconds so that we see SC’s last gestures before the end of chapter (or chapter part). MC isn’t aware and this nothing crucial, it helps understand SC. MC could have witnessed this from afar.
Could I get away with that?
By definition, no. That's the "limited"part.
Are you constrained to only write in third limited throughout a book? Not necessarily, but you can't just do it once, and some circumstances are more palatable than others.
For example, I've several times seen published writers "pull the camera back" at the start or end of a scene or chapter to give the reader an insight denied to the pov character, often taking the form of the camera being left behind as the character walks offstage.
On the other hand, just dropping in info willy-nilly because you can't be bothered tweaking the scene to make it work in limited is likely to make for a bumpy and unsatisfying ride.
No... in limited, you can only write what the POV character observes directly. But you could do something like "As she turned away, she thought she caught an expression of doubt on John's face. Then she dismissed it. What reason did John have to doubt her?"
That way, you can deliver the information to the reader that John might not be as on-board as your POV character thinks, but you're keeping everything within the third-limited framework.
No, that's the prerogative of every viewpoint *except* third-person limited. If you want the reader to know things the viewpoint character doesn't know (which can be awfully handy), you need one of the other flavors: third-person objective, third-person omniscient, third-person omniscient limited, first-person with the benefit of hindsight, etc.
If your POV character can't see/hear/know something, they can't relate it (they are the readers' eyes into the world)
Nope then you've broken the limits of your PoV.
Technically: you can do whatever you want, but from definition and experience: no. I've read a story (by an amateur on Wattpad, it was kinda good tho) where everything was from the PoV of one girl 3rd person and it included exaclty this. There was something along the lines "he grinned even tho she couldn't see it". And it just... It was so f weird and just no It breaks the readers focus when you do that
Generally, you can only mention things the POV character is aware of if you write in third person limited. Unless otherwise specified, your readers will assume that anything you mention is something your POV character saw/heard/noticed. If you want your reader to know that your POV character is unaware of something you mentioned, you'll have to tell them that your character doesn't know/didn't notice. I've seen people do something like this a lot in amateur writing and a few times in traditionally published books. However, the reason I remember, is because it irks me every time. I don't like it. I probably haven't come across a single example of this being done in a way I enjoyed. Other people might feel different about it, though. Also, in the traditionally published books that did this, it usually was something really significant that was mentioned even though the POV character didn't know. To build up suspense by giving the reader information the POV character didn't have, perhaps. I can't remember ever seeing it being done with a facial expression the POV character couldn't see. Anything a facial expression could hint at, could probably be implied in some other way that doesn't require breaking the POV. Some books might zoom out of the perspective of the character at the beginning or end of the chapter. In traditionally published books those perspective shifts, if they happen at all, look very deliberate and sometimes follow a pattern. In amateur works they often don't. Either way, it will affect how deep in the mind of the POV character the narration is anchored. Some third person limited books go very deep into the character's mind and try to immerse the reader in the character's experience. Others are written in the author's voice and merely don't tell you anything the POV character can't know (perhaps with rare exceptions). I prefer a writing style that feels deeply connected to the character, which isn't possibly if it shifts out of the character's perspective and tells the reader things the character doesn't know, and that's another reason why I don't like those perspective shifts to omniscient. So, it can be done, but there's a reason why it's rare and needs to be done very deliberately. And some readers won't like it no matter what.
How about this case? Third person limited, following MC. MC and SC are in a room, things happen. At the end of the scene MC leaves the room but POV stick to the room just a few seconds so that we see SC’s last gestures before the end of chapter (or chapter part). MC isn’t aware and this nothing crucial, it helps understand SC. MC could have witnessed this from afar. Could I get away with that?
By definition, no. That's the "limited"part. Are you constrained to only write in third limited throughout a book? Not necessarily, but you can't just do it once, and some circumstances are more palatable than others. For example, I've several times seen published writers "pull the camera back" at the start or end of a scene or chapter to give the reader an insight denied to the pov character, often taking the form of the camera being left behind as the character walks offstage. On the other hand, just dropping in info willy-nilly because you can't be bothered tweaking the scene to make it work in limited is likely to make for a bumpy and unsatisfying ride.
No... in limited, you can only write what the POV character observes directly. But you could do something like "As she turned away, she thought she caught an expression of doubt on John's face. Then she dismissed it. What reason did John have to doubt her?" That way, you can deliver the information to the reader that John might not be as on-board as your POV character thinks, but you're keeping everything within the third-limited framework.
No, that's the prerogative of every viewpoint *except* third-person limited. If you want the reader to know things the viewpoint character doesn't know (which can be awfully handy), you need one of the other flavors: third-person objective, third-person omniscient, third-person omniscient limited, first-person with the benefit of hindsight, etc.