Does UI designers have insanely good imagination?

Do yall imagine the entire website in ur head? Like how do yall come up with nice looking websites? I cant understand. Ive tried my hardest to train my brain to come up with non existent designs in my brain and they look like ass and i design like ass aswell and maybe those two things are linked connected together? Maybe if i was able to have better designs in my imagination than i would be way better? How do i even train this thing? I am confused asf