A secondary form of appearance..? You even specified human, so I cannot say shark. I would eat so many people alive xD
I dunno. I’m generally quite happy with my body’s appearance. Due to my personality and also my career, I value my intelligence and abilities a lot more than my physical appearance. I may be a young investigator, but I am an author/ co-author on 10 peer-reviewed scientific articles right now. It may not be apparent what that means to you, but let’s say that my career is seemingly having a useful output. Both looks and intelligence will eventually fade away, and both these attributes can result in new content. I would not argue one is more important than the other, but I personally value intellectual and especially scientific output to be more valuable than content produced from appearances.
In a way, ‘coucherequin’ is my secondary form; like a persona. Of course, coucherequin is real, i.e. it’s me. Ageplay is something that I enter and exit, like what you described. That doesn’t answer your Ask, though. I doubt that I would want to temporarily shift into a different age, if that would involve me losing part of my mind. Though, I think that I’d look cuter if I could shift into a smaller version of myself ^^. My Dutch heritage made me a little tall. Through the magic of photography, I try to make myself look smaller and cuter than what I am. (Though I don’t edit my pictures with photoshop or anything like that). If I was able to become the smoller and cuter version of myself for real, this would all be a lot easier!!