We have a "Change pose"... So why not use the same tech that is used to make the expression emotes, for a couple of different semblances for a "Change expression"?

I'd love to have my character's default facial expression not looking like he's always too concerned with the roast in the oven.

A more happy face, a slightly tired look or some distant eyes. There are many subtle details that despite being small, can completely change how a character face is perceived.