To view an event of a specific calendar with more details, you have two ways:
The first way
Hover your cursor over the event to see its detailed view.
The second way
Right-click the event in the Calendar View pane, then select View from the drop-down menu.
The Preview form will appear.
At the Preview form, if the event includes attachments, you can download them by directly clicking its title. If the attachment is an image, you can also click View to preview it.