The Wallet Passes docs, https://developer.apple.com/documentation/walletpasses seem to be missing any information about the features coming in iOS 18, specifically the new posterEventType, new semantic tags, and how to build out the event guide for a given ticket.
WWDC24 session: https://developer.apple.com/wwdc24/10108
I was looking for this too. In the session they say "download the sample code below to see all the new pass ticketing updates in action" but there is no sample code attached.
It is probably too early for documentation and sample release. I think they will come out soon, maybe with beta 2.
By the way, for what I've been able to understand, the new eventTicket format is an NFC only, so I think you'll need to provide NFC data for it to show up.
While a documentation or a guide is still missing, we were able to understand how to generate it, on passkit-generator. WWDC video is wrong.