I’ve seen sometime pages order their games based on category (like “game jams”, “big projects” , etc)…

How could I go about to do this?

You can create collections of project pages - including your own. So for example, if you have some platformer games and some game jam entries, you could each put into a corresponding collection you have created. You can then set this collection to be public and add it via the 'Edit Theme' feature on your profile page. You can also rearrange the order in which the collections will appear from there, and you can change the order of a collection's items from within your library.