Any...

I love everything by naono bohra but i am not sure what you meen by old manga style sorry. I hope you enjoy it, it is very good.

http://www.mangago.zone/read-manga/the_prince_and_his_mischievous_one/
http://www.mangago.zone/read-manga/kiss_the_abyss/
Once a upon a fairy tale
In here it has 6 chapters but you can read it in webtoon for free
http://www.mangago.zone/read-manga/mo_dao_zu_shi_novel/
http://www.mangago.zone/read-manga/tale_of_the_yellow_dragon/?uprF

I mean this kind of art style
http://www.mangago.zone/read-manga/silver_diamond/

Thanks. This is literally what I want

You don't want manga or just that art style in general

Just the art style