Microsoft is probably foreseeing a lot of support requests so they joined Apple and provided tenant admins a way for iPhones running iOS 15.6 to automatically exchange user credentials for OAuth token, migrating devices from Basic Authentication to Modern Authentication.
We've made a to the point post on how to do it along with other protocols (IMAP, SMTP) and Microsoft has released a detail post also.
This should make things easier not forcing users to re-configure their iPhones Mail Apps accounts to get modern authentication.
