User Configuration > Administrative Templates > Microsoft Office 2016 > Miscellaneous
User
HKCU\software\policies\microsoft\office\16.0\common\fileio
This policy setting controls whether Word, Excel, and PowerPoint users can use non-cloud locations (local and network) to create new files. If you enable this policy setting, users will only have Cloud Locations available to perform SaveAs and Save new files. If you disable or don’t configure this policy setting, users can use any location (Cloud, Local, and Network) to perform SaveAs and Save new files. Note: This policy setting only applies to subscription versions of Office, such as Microsoft 365 Apps for Enterprise.