I usually create a file in google docs and write description of the lore, details about the world, and which characters are part of that universe. When I have doubts, sometimes I use Gemini to help me figure out what would be interesting to add or improve—I also ask my friends their thoughts about.
But if it's something from other cultures that aren't from my country, I usually do a little research to gain a better understanding before putting my ideas into practice.