I think I'd like to see what people would do in their leisure time or domestic work . You see so many stories about travel and war, but you rarely see people interact outside of that. And if you do, it's usually not made unique for a setting that isn't Earth.
What cutlery do they use? What does a morning routine look like? In a world where fire magic is commonplace, how do they cook? How would those things evolve over centuries?
Fantasy especially feels stagnant for this, but I think sci-fi is guilty of this too. Are there things in specific works where an innocuous detail made you wonder more about how a setting worked?
One of my favourite minute details about Neuromancer is exactly this. A one-off background character, a bartender, is described as having an outdated, clunky old cybernetic arm, which you don't really see in modern cyberpunk. Everyone has shiny and modern stuff, even "last gen" when it shows up is indistinguishable
I remember that. There's a character in the game Observer like that as well, with shitty low-cost prosthetics all the VA equivalent would pay for, it's implied