Level Loading for Games

Hello, so I am kind of confused on what you would do for level loading in a game, as I am only starting to really think about the size of the project for making a game. For example, in UE4, would you keep all of the levels in one single project, loading each at the time you need them for advancing through the game, would you make each level in a separate project, loading them and your progress using programming to open and store the files, or maybe something else? If anyone could give an answer, thanks!

You can make separate levels inside one project. I’d only use another project for another game or to test unstable stuff out.