Noroware Oujo wa Mahou Shokubutsu wo Kenkyuu shitai: Koushaku-sama ga Konyakusha!? Watashi, Noroi de Youjo ni Natteiru no desu ga @comic

Charlotte, the third princess of the Kingdom of Forsyth, was treated poorly as a fake princess. One day, a mysterious man bursts into a ball and curses her while protecting her sister. She is confined to a villa in the north under the pretext of medical treatment... but the curse has turned her into a little girl?! She makes a fresh start and devotes herself to researching magical plants, but then she receives a letter.

"Waah! I'm engaged?!"

When she meets Leon, the head of the duke's family, she accidentally lies to him about her little girl appearance, saying she's "Shirley, the maid!"

The destinies of the two begin to move -- a thrilling love fantasy about a cursed princess and a handsome duke!!

https://www.cmoa.jp/title/330388/