How to use demo content inside plugin?

Hi, I am total a newbie.

I would like to know how to try demos inside the plugin

Installed this one Directional & Planet Gravity in Code Plugins - UE Marketplace

Have read this guide Plugins | Unreal Engine Documentation
But still, I do not understand what I am missing.

It is activated and ready to use.
For demo new minimal default project was created, or I should somehow create project from a plugin?