I also would like that. Having potions/fish that allow you adjust thralls would be great. With exception to Lianeele, most dancers are flat as a board.
Also, I’ve noticed that some thralls I’ve captured do not have eyebrows. Having access to adjust thrall features would be nice.
Having those effects to change my character would be great as well. I wouldn’t have to lose all my progress just because I want to tinker with my character’s features.