Basic question on how to make visual game output scaleable / i.e. able to double size

I’m making a game in 640 by 360. How can I make it so that the visual game output can be scaled while keeping the aspect ratio? For example, I’m trying to simply get it to double the game size, but I’m having trouble with this. I’ve played with the display settings under project settings and they either do nothing or end up breaking the game. I know this is basic, but I don’t see much online about how to do this.

In the project settings Viewport and Integer scaling should work.