Setting User Roles in Firebase

Question: How can we implement user roles like admin, consultant, and client in our app using Firestore? We want users to select their role during signup, store this data in Firestore, and then grant them access to specific areas of the app based on their role. After setting up the role rules in Firebase, how can we apply them in Nowa?
So we need admin to choose other admins users in the users page. The other option is to create sign up pages for each role. So if a consultant is signing up, we can place a questionnaire or button w/three choices: What’s your role? A. Consultant B. Client. So Maybe an office worker w/Admin privileges uses the consultant sign up