It really depends on the AUDIENCE.
Do you write Romance story with the usual broad chest ikemen for romance thirsty female ?
Action thrill with fights and battle of chunibyou warrior for young boys ?
Rom Com with comedy for mainstream people that love normal romance story ?
Mindless Harem with big booby whore aunties for desperate NEET man ?
Boys Love with Broad chest man with Korean hairstyles that doesn't fit the era but satisfying for Fujoshi ?
Or Girls Love story with Queer, Futa, Pegged man, and other forced LGHDTV+ propaganda that doesn't reflect the moral values of medieval world and the world the character reincarnated, but it satisfy the whole community of Scribble Hub because they feel "represented" (even tho the correct term is "Self-Inserted") ?
Maybe a story for blatant male that wanted to be converted to women via death and become girls love because they reject natural hormon and go full lesbian without thought ? Or maybe a Male inside Female that date with male from another world and became hidden gay couple that only themselves know ?
*****
Well, I'm rather lazy to answer your question. Sorry for that. But those thing above where the usual cliches that appear in the "reincarnated as...." Stories.
Please make sure your story has depth in character. Or just make them have "likeable" personality and solve problem the "adult" way, no matter if the conflict can realistically be solved by "modern adult discussion" or not.
Just ignore the logic that people of medieval will be angry and ignore our modern world style of solving problem as "heretic" and "unorthodox".
Also don't make the character look weak and indecisive. Readers don't really care of characters have feeling and moment of lapse. They want a strong and handsome knight that act like gentlemen, with a twist that he has sickness with women, so that our Self Insert women (or man, if it's Boys love) can cure him with power of feelings and romance.
Make sure the romance is hidden and open ending, so you can always make more episode containing more and more fluff 'fan-service' flirting than actual couples (or gay couple) who have been married for a long time.
Okay. Sorry again for rambling and venting my frustrations with 379 words instead of actually answer your question.