Show duration of event Apple Calendar
Yes.  When you create (or Edit) an event, you can click on the Start time, enter it, and then click on the End time, and enter that as well.  You can also make the event  All-Day.  These options are in the same window used to create the event.

To start the process, just double-click or right-click on the day of the event.  Your options will immediately be apparent.  You Title/Name the event,, enter the location now, later, or never.  If the window closes before you finish, double-click the event to edit for the times, notes etc.  Right-click will get you the same options.  Get Info on the event will also work for editing.