I don’t think there’s a too big for a simulation type game world, go all the way. But for more directed game styles that are narrative driven or more carnival ride than simulation don’t make it boring use techniques from past games; the keeping distant landmarks in view outside like in New Vegas, or hilly landscapes to obscure stuff to discover like in Zelda or Skyrim. Bad examples would be like traveling between towns in daggerfall or those monuments in the middle of nowhere in starfield.