Configure the fraud alert feature so that your users can report fraudulent attempts to access their resources. Users can report fraud attempts by using the mobile app or through their phone.
Configuration options include:
Block user when fraud is reported: If a user reports fraud, their account is blocked for 90 days or until an administrator unblocks their account. An administrator can review sign-ins by using the sign-in report, and take appropriate action to prevent future fraud. An administrator can then unblock the user's account.
References:
https://docs.microsoft.com/en-us/azure/active-directory/authentication/howto-mfa- mfasettings#fraud-alert