Think of the universe as a painting. There’s the image made in paint, and the surface it was painted on. The canvas.
The stars, the planets, the gasses, the matter and energy and even the space between are the paint. What’s the canvas? Is there a canvas? Would the canvas follow the same rules as the paint?
Well if you think of our universe as a flat image, you could technically picture it as an ever expanding “canvas” ,like the reddit and lemmy thing, and as all the other planets and stars change and move so does that magical canvas of the universe.