.net 3.1

If I simply add netcoreapp6.1 in the targetframeworks which targeted netcoreapp6.1 and build a framework dependent release would it work? or would it break or need to upgrade the entire application?

I've been trying to learn .NET Core after first learning the Framework structure. I am still learning regular views, which utilize Razor code, but I'm coming across a lot of Razor page info. Is it now, or will it ever be a structure of Models, Razor Pages, and Controllers? -A curious learner.

Does anyone know how to configure their project to pull from a Nexus Re