You can just create a local repo with git init, and then never push to a (non existent) remote repository. Git is decentralized, meaning that you always have a functional and complete repo when you’re working with it.

Depending on your tooling, you probably have a GUI for git if you’re a noob, which can usually “initialize a git repo” for you. I use the cli/lagygit tui, so I can’t help with that.