is-admin.ts

// You can create a function in your authentication provider that resolves the value of admin:

isAsdmin(): Promise<any> {
  return new Promise( (resolve, reject ) => {
    firebase.database().ref(`userProfile/${userId}/admin`).once('value', adminSnapshot => {
      resolve(adminSnapshot.val());
    });
  });
}


// That will return wither tru or false, then you call it from the class:
  
constructor(public navCtrl: NavController, public authData: AuthData) {
  authData.isAsdmin().then( adminStatus => {
    this.isAdmin = adminStatus;
  });

}
  
// Then is just a matter of calling it inside the html:
  
<ion-content padding>
  <div *ngIf="isAdmin">
    <h3>Hey Admin!</h3>
    <p>What would you like to do?</p>
  </div>

  <div *ngIf="!isAdmin">
    <h3>Hey Regular User!</h3>
    <p>What would you like to do?</p>
  </div>
</ion-content>