So your Wanderer is lumpen and balding and rocks an aggressive form of psoriasis which pre-war doctors were unable to touch. That snazzy Vault-Tec jumpsuit is the post-apocalyptic equivalent of a leper's bell—even Dogmeat looks worried. But if you're the sort of person who wants Super Mutants to cross the road to avoid you that little bit quicker, modder FancyPants has just the thing: a few dozen new facial joints.
Immersive Facial Expressions does everything it says on the label and more. From the Fallout 4 Nexus:
"This mod gives the most immersive, top of the line facial animations you will ever see. Do you ever find yourself wandering the wasteland, and thinking to yourself 'why does every face not look more immersive', of course you do, we all do. This mod changes that."
I feel like I'm there.
Assuming you don't want to turn the Commonwealth into a radioactive hall of mirrors, there is apparently a serious version of the mod in development, aimed at making Fallout's faces less mask-like. Until then, you can roleplay a boa constrictor.