Thread for new members to post their Sims 3 game issues (2020-22 version!)

Please some tips, advice for beginners - own world creation? I downloaded a tutorial that shows how to use the program, tools, and so on, but I still need to explain more clearly how to create the world. For example, I have no idea how big what should be to make it look as realistic as possible, if you understand me. I mean the surroundings, like mountains, rivers, etc.