How to managed IOS OS 10.0 -11.0 with Modern authentication

[aussupport]

Scenario: Client has existing iPhone's already in use - 90% use native iOS App - We want to force these devices into MDM Enrollment (via Intune) and Force them to use MS Outlook APP.

Currently, 50+ devices are between 10 and 11 OS version. Rest are 11+ 

Need to move all these IOS users for modern auth before Oct 2020 without any business impact. 

https://docs.microsoft.com/fr-fr/azure/active-directory/conditional-access/app-based-conditional-acc...

SA

[#2]

I would setup your entire Intune environment first with all the policies you desire + configuration for the Outlook app (app configuration policy, so all the settings are configured for a user).

Document everything and announce users should move to the new MDM system.
Put an end date for the migration.

At that end date, enable conditional access policies to require a compliant device/ approved app for Office 365