You may want to stop end users from Accessing the Azure AD portal, as they can all view all user accounts and the email addresses associated with user accounts.
Follow the steps below to block user from Accessing Azure AD.
Login to Azure as global admin
Go the Azure AD > User Settings
Also select ‘No‘ for ‘Users can register applications’
Select ‘Yes‘ to ‘Restrict access to Azure AD administration portal’
Optional – Select ‘No‘ for ‘LinkedIn account connections’
End users will now be unable to view other users email addresses and names in Azure AD.