Yeah, in the real world there is no upside down in space.
But if you look at Star Wars or especially Star Trek, you will notice that the ships always are like horizontally aligned. It is a normal thing in movies to make “it look good”.
Yeah, I’ve noticed that. It’s become a pet peeve of mine.
Why?
Can you imagine how hard it would be to tell a story if spaceships didn’t stay “upright” most of the time. It’d also be very disorientating to watch. It would make scientific sense, but in cinematically it would be an absolute mess.
(Also SW is basically just Middle-Earth in space. It’s not exactly known for its scientific accuracy.)