DIFFERENT stories/spin-offs in ONE HUGE Universe? who did it ?

Fellow worldbuilders and story tellers… Hi!

INFO DUMP me with your world building.
I’m curious to know if anyone here has ever built a colossal world that is spread out across sprawling areas filled with so much divergence it makes my head spin, like that of league of legends : vast nations , different cultures , magical systems and histories that might overlap and influence each other anywhere. I would love to discuss with someone how to come up with such a world.

For me , it's for a novel . but you guys even if you are working on a game or a manga ... I still want to know about it. It would be fun and also exciting.

I am planning w to produce several stories that are seperate but happen at the same time in different locations or different times.
Some novels will take place in one location, some will be detailed with 2 or more regions, and some of the bigger nations will have more diverse story arcs and elements. I also want to incorporate these nations with indirect relationships, or latent influences, with Easter eggs or characters that transpose between books.

Share any experience, challenges or resources you’ve come across!
I’m excited to read and share how you advise!