try reading Ouji-sama Nante Iranai
I may know of some lemme go through meh list brb
https://www.mangago.zone/read-manga/i_favor_the_villainess/
https://www.mangago.zone/read-manga/mage_demon_queen/ (obvi by the title prolly already read since its popular and on webtoon)
https://www.mangago.zone/read-manga/her_shimcheong/ (Not royalty but nobility, the love interest is the wife of a lord)
https://www.mangago.zone/read-manga/the_hidden_love_of_the_young_mistress_and_her_maid/
https://www.mangago.zone/read-manga/the_villainess_and_the_woman_who_would_do_anything_for_the_sake_of_love/
https://www.mangago.zone/read-manga/will_we_live_happily_ever_after/
https://www.mangago.zone/read-manga/hi_my_lady/
https://www.mangago.zone/read-manga/marie_and_alex/
https://www.mangago.zone/read-manga/my_demon_secretary/ (demon princess)
https://www.mangago.zone/read-manga/ghosts_of_greywoods/
Most were either short or nobility ;; sorry theres not a whole lot of royalty type yuri that I know of
do yall know any like royalty? yuri