Horizon Forbidden West added a "photo mode", I think mostly just to show off how good the graphics can be (when nothing is being animated). It does look awesome. If you zoom the camera in, you get anatomically correct facial features.
There might also be some conversation scenes with close-ups of Aloy. Depending on your graphics settings, you might get some extra details rendered.
I am absolutely convinced that the game is not rendering fine hairs while you're fighting robot dinosaurs, since, as you suggest, that would be kind of ridiculous.
But, hey, you really kicked the shit out of that straw man! Great job!
Yeah! That's why I put all of my secrets directly into the code.