User Configuration > Administrative Templates > Microsoft Project 2016 > Project Options > Calendar
User
HKCU\software\policies\microsoft\office\16.0\ms project\options\calendar
Specifies the finish time that Project assigns to tasks by default when you enter a finish date without specifying a time. If you enable this setting, new tasks where the user does not enter an end time will have the end time that you specified. If you disable or do not configure this setting, the user's default setting is used.