How to create admin user etc in firebase?

Question

firebase

I don’t quite understand how to make users with different rights, here are the rules:

{
  "rules": {
    "authentication": {
      "users": {
        "$uid": {
          ".read": "auth.uid == $uid || root.child('authentication').child('users').child('auth.uid').child('isAdmin').val() == true",
          ".write": "newData.parent().parent().parent().child('authentication').child('users').child('auth.uid').child('isAdmin').val() == true",
          ".indexOn": [
            "email"
          ]
        }
      }
   }
 }
}

User:
prntscr.com/d1qg4k
Base:
prntscr.com/d1qh51
Are there any examples?)
Thank you!