Just to clarify how this was done before the thread is closed, because it ranks high on google but the solution is still pretty vague.
Creating static heads appears to not be very well documented. There are threads and official statements suggesting they shouldnt even exist, however the catalog is rife with them. There is a little icon designating animatable heads as such, but if static heads arent allowed why are there ANY heads that dont have this icon??
Not that the icon necessarily means anything, as some “static” heads have been given this icon Big Troll Head - Roblox
This head doesnt even have a face controls instance when imported and is given the animatable head icon!
So my only assumption is people are using niche exploits that allow them to upload these heads. This head is from October 2023, around the time Dynamic Heads were first introduced, so I would assume whatever the troll head did has been patched.
Regarding the more current heads like the ones shown, I think I know how they did it. It does NOT involve creating a “smaller head inside a larger head”. In fact I assume that method is what got the “Scaredy” head removed. That head is now removed…
Face Controls Demo - Creator Store (roblox.com)
Ive uploaded one of the static heads as a development item so you can see what I mean.
Here I have used the “Jaw Drop” face control. See how it moves the head? Kind of in a non-sensible way, but it does. The head has moved. The face control exists. Therefore- validated. Try the other face controls, some of them move the head ever-so-slightly. I assume they reused the blocky rig template
https://prod.docsiteassets.roblox.com/assets/avatar/dynamic-heads/reference-files/BlockyCharacter.fbx Like the solution suggests, then used this texture
Ville Valo - Roblox
The model for this head doesnt include separate eyes or a mouth even. Its impossible for us to see where the bones are as studio converts them into the face controls instance, but they are there, weight painted to weird vertices.