Recommened me some BL where it involves royalty 👉👈 Prince x Servant / Prince x Princ...

don't mind me-(￣∇￣")

this might be what your looking for but it recently started
http://www.mangago.me/read-manga/duke_s_private_tutor/

http:/0/www.mangago.me/read-manga/duke_s_private_tutor/ (not a servant, he's a tutor)

http://www.mangago.me/read-manga/ouji_sama_no_ryuu/ (not a servant, he's a hotel worker

http://www.mangago.me/read-manga/yuuutsu_na_asa/ (he's not royalty though, just nobility. an earl or viscount to be exact.)

http://www.mangago.me/read-manga/solar_eclipse/ (not a servant, he's a stand-in knight though)

Kings Maker is the reason why i wanted to read more Royalty type BL

The Prince and His Mischievous One
http://www.mangago.me/read-manga/the_prince_and_his_mischievous_one/