Here's an intriguing little sub-subgenre of transgender transformation: Characters turning into their own mothers. Some people seem a little uncomfortable about it, maybe out of an aversion to potential Oedipal themes, but personally I feel it's more about a weird "unifying" thing between offspring and mother where the allure lies in BECOMING the parent, as opposed to...well, all the sordid Oedipal/Electra stuff.
Anyway, a lot of this kind of art is drawn by a fellow called ThatFreakGivz. You can find out more about him at his Patreon page:
https://www.patreon.com/thatfreakgivz
His style needs further development, but I think he does have a talent that's steadily evolving. Here's one I commissioned from him with Tenchi (from "Tenchi Muyo") transforming into his mom, Achika.