Well, it's just a simple mouth opening – the lower jaw drops, and so on... if you leave it like that without a throat, the mouth opens, and there's nothing inside ))) it just looks awkward.
P.S. The jaw is almost the simplest thing in animation... I'm not talking about emotions, but looking at the Total War series, you can see the jaw movement of units in a regular battle, while animated emotions are only in cinematic cutscenes.
Added 7 minutes ago
Today, I retopologized the hair and dress, plus added a throat and teeth... I trimmed the body hidden by the dress and hair; in short, all together – hair, body, dress, eyes, teeth – is 15500 triangles... but they are all separate meshes – the largest of them is the body with 10000... well, I might be able to reduce the polygons on the shoes by another 1000-1500... that's it, but there's also a fur cloak, so... and all the throne accessories are 9000 triangles.
How do these numbers look?
Added 4 minutes ago