@Draeze
https://mangadex.org/title/51376/reincarnated-as-an-aristocrat-with-an-appraisal-skill (rebuilding family power)
https://mangadex.org/title/20393/choujin-koukousei-tachi-wa-isekai-demo-yoyuu-de-ikinuku-you-desu (introducing democracy in another world)
https://mangadex.org/title/15553/tensei-shitara-slime-datta-ken (making a nation of monsters)
https://mangadex.org/title/21809/genjitsushugi-yuusha-no-oukoku-saikenki (perfect for what you're looking for)