I need an example project using Firebase features to control the number of users authenticated simultaneously on different devices

I need an example project using Firebase features to control the number of users authenticated simultaneously on different devices There must be a control made by the user's email where it will be informed how many accesses the user can have simultaneously. THE Storage of this control must be in Firebase Realtime Database or Firebase Firestore. Whenever the user logs in via Firebase Authentication, it will be verified how many devices have this user's active login. If the number of devices is greater than allowed, the first device with an active login must be disconnected. All code must be made using Firebase resources (Authentication, Cloud Functions, Realtime Data Base, Firestore). To validate the project, a simple Login and Logout model is necessary so that I can perform the test. In order for me to test the number of active users simultaneously, there must also be a simple model where I can determine, by the user's email, how many simultaneous devices he can have.