It's not a library. No components ship with Lit. It's just syntactic sugar for stuff that's built into browsers now. That's the "bare metal" parts. You need to write your own components and make your own library for your company or project, although some big firms like IBM, Alaska Airlines, and MS have released the libraries they made with it.

This fact, that it's the "anti-framework" (ie: not a framework) is both its greatest advantage and its biggest source of confusion for new folks.