Please check our documentation on how to add tags for user using different SDKs and Server API:
Server API - Authentication | Users | Create User | QuickBlox
iOS SDK - Users | iOS SDK | QuickBlox
Android SDK - Users | Android SDK | QuickBlox
React Native SDK - Users | React Native SDK | QuickBlox
Flutter SDK - Users | Flutter SDK | QuickBlox
Feel free to check our official documentation for more information that will help you to integrate QuickBlox services into your applications / projects or contact our Support team by submitting a ticket if you have any other questions.