You would need to combine the body texture and head texture in the material, lerp them together for the final RGB output. The head texture would be of same dimensions/frames/facing angles. Plug the head texture alpha into the lerp alpha so it blends properly.
It can work, but when you want to show different weapons too, you’d need another layer for the weapon texture, but you might find they don’t fit into the same dimensions (overflow to other frames).
Another way is to modify the material to know how to layer a single weapon sprite in, and set its position properly for each frame (transform). So you’d need to feed lots of this data into the material for this.
Another way is to use flipbooks and sprite sockets, but that has a lot of issues too, like draw order, bulk editing custom pivots/sockets seems to be locked out, not being able to preview sprite sockets with a sprite, etc.
It’s no easy task to get it all working.
Here is a very modern take: Bone Sprite Animation System