If you refer to the cruel world maybe Reverend Insanity but that's very different in vibes because the protagonist is the most evil of them all.
If you refer to Manhua as in chinese cultivation stories, I like Serpent Ancestor
If you refer to the Family there's nothing like this I can think of. For a story about the creation and rise of a clan, there's a Light Novel called "Starting From A Son In Law To Build An Long Lasting Family" where the MC increases his cultivation by procreating and making his children progress. He has over a hundred kids, and as the MC progresses his kids become stronger because he can obtain more resources or the kids are born with better Spiritual Roots. It doesn't have the same feeling of Legacy because it's mostly about his direct children and the farthest relevant descendant is a grandson. He has a dozen wives and a lot of concubines but after a certain point he focuses on procreating with high level female cultivators. It's spicy but not "sm**".