How do you instantiate a prefab without already having an existing instance of the prefab?

Questions & Answers
1

How can I instantiate a prefab without already having a reference to an existing instance?

2

You either make a script that has a GameObject field (or a component that is on the prefab) exposed in the inspector and manually assign the prefab (from the Project tab) in the editor.

A more dynamic way is to load it from resources - Docs with an example