Lost Omens Legends is far and away the best setting sourcebook I've read for a ttrpg. While books like the Lost Omens Character Guide and Gods And Magic focus on providing gameplay mechanics to reflect ancestries, religions, regions, and organizations, Legends has a solid focus on painting in the details of the world. The character sketches in the book and the relationships and conflicts between them provide both great narrative seeds for adventures, as well as excellent models of the diverse people inhabiting Golarion that can provide inspiration for unique and exciting player and NPC builds.