When a ticket buyer has purchased a ticket from you, you can choose to include an ‘add to calendar’ link in their event confirmation email. They will then be able to add your event to their Google, Apple, Office, Outlook and Yahoo calendars.
Simply use the ‘Add to calendar’ link 'placeholder' in your event confirmation.
For more details, please refer to this article about how to edit an order confirmation or send a message to customer support.