Kanojo ni naru hi falls under the gender bender genre, though i still recommend it for 1 wholesomeness, 1 chapter melodrama and likable-ish characters.
The sequel/spin-off may be more to your liking because the one getting gender bent is in denial over her change and still acts and dresses like a boy, however i find the characters significantly less likable than the prequel and promptly drop it. But hey give both of em a shot.
https://mangadex.org/title/10507/kanojo-ni-naru-hi-another
There's also Emperor and the female knight, a medieval no-fantasy manwha about a woman who was cast out of her family. In order to survive she worked as a mercenary and through circumstances now becomes a soldier/knight for a fledgling country. The heroine looks very masculine and it doesn't look like she's gonna become more feminine... like ever, so i didn't read far before dropping it. But if the only thing you need is a vageen then knock yourself out
https://mangadex.org/title/42278/emperor-and-the-female-knight
Gekkan Shoujo Nozaki-kun, If you have watched the anime then you know who it is. If you haven't, well the reverse trap is more of a gag character and looks rather androgynous (though not as much as the female knights). The reverse trap isn't a heroine rather a friend of a friend. If you only want a reverse trap in the manga and uses it for jokes then give it a read.
https://mangadex.org/title/1880/gekkan-shoujo-nozaki-kun
Is it Tough Being a friend, has a more feminine reverse trap (when compared to the two manga above), I cant say much about it because it's spoilers. The manga is fairly new but the chapters that are already translated reveals and has a chapter focusing on the reverse trap. Although reading the comments say that in the future theres going to be NTR elements however current translations havent reached that point yet and i think it's still far off. If that's a big taboo for you, you can read until you smell the beginings of NTR and drop it or skip it entirely
https://mangadex.org/title/43551/is-it-tough-being-a-friend
Mayo chiki is about a misogynist sorry i missread that, a gynophobic guy who has hijinks with the butler who is actually a girl. The reverse-trap is the heroine, go read it.
https://mangadex.org/title/17/mayo-chiki
Nisekoi is a harem manga. IIRC one of the rivals-turned heroine is a reverse trap, I don't know who, and I don't know if she stays a reverse trap. I couldn't get myself interested in the manga tbh. But if you're desperate for reverse-trap then happy digging.
https://mangadex.org/title/951/nisekoi
Infinite Stratos, has a heroine start-off as a reverse trap but after her introductory arc she stays looking like a girl, She's best girl tho so if ya only want reverse traps just read her arc. Though I have only watched the Anime so i don't know which chapter she's introduced.
https://mangadex.org/title/425/infinite-stratos
Ruler of the land, is an old school korean martial arts adventure fantasy manwha that has the heroine start off as male-looking but eventually her sex is revealed and become the protag's heroine. Although she's supposed to be a warrior in the same footing as the protag, she ends up being the damsel in disstress most of the time so it can get frustrating. Her looks don't change for the entirety of the manwha however she looks quite feminine. So no Female Knight swoll.
https://mangadex.org/title/660/the-ruler-of-the-land
That's all on top of my head, I'll add more once I remember/find more reverse-traps. Mangadex should make a tag for those.
