The ability to view shared calendars on an Apple iPhone using the built-in Mail and Calendar app depends on how the shared calendars are set up in your Office 365 environment.
If the shared calendars are created as "group calendars" in Office 365, then they should be visible in the Calendar app on your iPhone. If the shared calendars are set up as "delegated calendars" for individual users, then they may not be visible in the Calendar app on your iPhone.
If you're unable to see shared calendars in the Calendar app, you may want to consider using the Outlook app for iOS, which is available in the App Store. The Outlook app is a full-featured email and calendar app that is integrated with Office 365 and supports viewing shared calendars.
To set up your Office 365 account in the Outlook app, you will need to enter your Office 365 email address and password, and follow the setup wizard to connect to your account. Once your account is set up, you should be able to view shared calendars in the Outlook app.
If you continue to experience issues with viewing shared calendars, you may want to reach out to your Office 365 administrator or Jamf support for further assistance.
