if i am to download a mesh from a site where i am given access to it, am i allowed to import it to new vegas and then also publicize it as a mod if it is resources from another game? Is this like a copyright issue? dont feel like getting sued over some dumb mod because im bad at 3d modeling

Bruh, as long as you don't post it where content like that is not allowed i.e. The Nexus, you won't get sued, hell, i'd say the worst thing that could happen if you do that is that you would end up banned, nothing more. As far as i know, you're welcome to post ported content over here, don't worry.

Have a noice day.