For Google Workspace.
How to restrict access for mail clients that use POP/IMAP/Sync?
In order to restrict the access to POP/IMAP from a mail client or to restrict the access to Google Sync from a smart device, set up the setting on the Google Workspace Admin Console.
Please refer to the Google Workspace Support site shown below.
Settings for IMAP and POP access
Google Workspace mobile management /settings
This settings is the Google Workspace feature.
For further details, please contact the Google Workspace.