I know of one manga with a similar story premise.
But can you become a magical girl?
http://www.process-productions.com/f...ad.php?t=41649
https://urasunday.com/mahoshojo/
A granny character transforms in chapter 7 of Ore to Hero to Mahou Shoujo
No English version is out but will be soon.
http://www.nettruyen.com/truyen-tran.../chap-4/274552
There's also this Hentai.
Magical Granny Orgasm☆Chiyo-san
https://hitomi.la/galleries/1307679.html