All the classic and new magical girl series I could find on here.
Includes female-to-male transformations.
Genres will range from light and fluffy to dark and gory to ecchi.
Mahou shoujo list part 2:
https://www.mangago.me/home/mangalist/2605937/Mahou shounen list:
https://www.mangago.me/home/mangalist/2367476/