User Configuration > Administrative Templates > Microsoft Outlook 2016 > Account Settings > Internet Calendars
User
HKCU\software\policies\microsoft\office\16.0\outlook\options\accounts
This policy setting allows you to deploy Internet Calendar subscriptions. If you enable this policy setting, the URLs listed here will be read and the corresponding Internet Calendar subscriptions will be added to each of the user's profiles. The name you specify here will not be used as the name of the Internet Calendar subscription. If you disable or do not configure this policy setting users will not have any default Internet Calendar subscriptions.