User Configuration > Administrative Templates > Microsoft Office 2016 > Manage Restricted Permissions
User
HKCU\software\policies\microsoft\office\16.0\common\drm
This policy setting will allow users with earlier versions of Office to read documents with browsers supporting Information Rights Management. If you enable this policy setting, users with earlier versions of Office can read documents with browsers supporting Information Rights Management. Note that this will make all documents with restricted permissions larger. If you disable or do not configure this policy setting, users with earlier versions of Office cannot read documents with browsers supporting Information Rights Management.