You can select between the Classic widget type and the Neo widget type. You can choose the widget type when creating an appointment for a new calendar or editing an existing one. You can make the changes by following these steps:
Navigate to Settings> Calendars> Click on “Create Calendar”
Select Calendar Type, you can choose between any of the available types
Team & Event Setup —--> Widget Type is where you would see the following options to select from:
Classic (which was used for Unassigned)
Neo (which will be used by default for Group Calendars)
Please Note:
You can also edit an existing Calendar and change the widget type for it.