In the case of iOS, it has restrictions to make a shortcut for internal apps of OfficeMail like Android. If you want to use a shortcut in iOS, the app should support the "Shortcut" feature.
https://support.apple.com/guide/shortcuts/create-a-custom-shortcut-apd84c576f8c/ios
But OfficeMail iOS doesn't support it yet. We're going to support the shortcut in the near future.
You have two options if you want to go to the OfficeMail Calendar directly.
1. Widget: you can see and open the calendar if you add the OfficeMail Calendar widget.
https://re-work.zendesk.com/hc/en-us/articles/7613916151695-How-to-make-a-calendar-widget-on-iPhone
2. You can access the OfficeMail Calendar directly if you press long the OfficeMail icon.