User Configuration > Administrative Templates > Microsoft Outlook 2016 > Outlook Options > Preferences > Calendar Options > Schedule View
User
HKCU\software\policies\microsoft\office\16.0\outlook\options\wunderbar
This policy setting controls auto switching of calendar layouts from horizontal to vertical. If you enable this policy setting, auto-switching is turned off. If you disable or do not configure this policy setting, auto-switching is turned on.