The Unity Package Manager Complete Guide Unity 2020 and above - Episode#1

I am confused about using the package manager since it has been updated over the last several years. It used to be possible to import the standard assets package that came with unity which included several prefab character controllers to add to a scene. Since the standard assets have become legacy assets it isnt possible to do so without running into debug problems. Is there a way to use the project manager to quickly add prefab character controllers?