Cuphead hc time
I hc that some of the bosses, and maybe other characters, have various forms besides what you see in the different stages. This includes the more “humanoid” forms. If they have this ability, the ones you see in the game is the form they’re the most powerful in.
Think of it like that one episode of Lilo and Stitch where Stitch wants to be bigger, and while he gets his wish, he’s not as strong as his regular, tiny size. The only difference being that the characters with this ability can control it at will