Hi there, Maria! Thanks for getting in touch, π
Tickets are considered products in WooCommerce. The events themselves are simply the “product page” for purchasing them.
Is it possible that the tickets are not set up to display in your WooCommerce product gallery? When editing a ticket in WooCommerce, try changing the catalog visibility for it from Hidden to Catalog in the Publish settings (screenshot). From there, you should be able to cross sell tickets like any other product in WooCommerce. Here is the WooCommerce documentation for setting up cross sells.
It’s worth noting that tickets will not cross sell themselves on event posts. However, related events will display on an events posts.
Does this help answer your question? Please let me know. π
Cheers!
Geoff