How do I acquire the knowledge of every Unity namespace and every Unity capability at my disposal?

Im new to Unity and I understand the whole using MagicalLibraryOfTools syntax …but i cannot find a list of all said magical libraries of predefined classes and their methods. I feel like a mother list like that would help me get a grasp on all the things i can do with Unity (that don’t require me reinventing the wheel)

The scripting API: Unity - Scripting API:

If you’re starting out, I recommend doing some tutorials, but for what you are asking for, the above is the “magical” scripting reference