Jonkisss

I just found this gem!!
https://www.mangago.me/read-manga/rumspringa_no_joukei/

Also here is a tag full of historical pieces, there are included non-bl ones tho but I'm sure you'll find some gems ^^
https://www.mangago.me/tag/Historical/

King's Maker
Two Souls
The Painter Behind the Curtain

and agree with Rumspringa no Joukei as well, a beautiful story

This one too ^^
https://www.mangago.me/read-manga/awairo_emaki/

These are frvt historical BL-

https://www.mangago.me/read-manga/yuuutsu_na_asa/
https://www.mangago.me/read-manga/a_proxy_painter/
https://www.mangago.me/read-manga/the_place_where_the_wind_blows/
https://www.mangago.me/read-manga/tamayura_yuki_ringo/
https://www.mangago.me/read-manga/an_abyss/

http://www.mangago.me/read-manga/it_s_not_like_that_gangto/

Thanksss