User Configuration > Administrative Templates > Microsoft Outlook 2016 > Outlook Options > Preferences > Calendar Options
User
HKCU\software\policies\microsoft\office\16.0\outlook\options\calendar
By default, users can share an entire calendar by saving it in the iCalendar format, or share a snapshot of a calendar by using e-mail. This setting allows you to specify the detail level in the shared versions of calendars, or to disable sharing of calendars.