Hey Math,
Nice to see you again and I hope all is well. 🙂
I think the only way to change the physical size of the ticket is to customize the layout of the email itself. You can do that by modifying the HTML and CSS of the email template, which is located here:
/wp-content/plugins/event-tickets/src/views/tickets/email.php
I know you’re familiar with how template overrides work, so overriding that template in your theme folder is the way to go about it.
Will this help you get started? Please let me know.
Cheers!
Geoff