Google Maps ? How to enable

This won't be available until apps are updated to support iOS 12. Such apps can't be published into the store until then. Your best bet is a TestFlight beta, though Google doesn't seem to offer one on iOS.

Anyone know if WAZE does?

This one will be interesting because Google Maps and Waze (owned by Google) will have to enable carplay support in the app. While I was pretty excited to see this change in iOS 12, it really didnt take iOS12 for this to happen. It is merely a policy change (jailbroken phones supported it for some time). Given the current policy of NOT allowing third party navigation apps in the app store, I don't see how we ever get this feature to test until iOS 12 is released and the app store starts allowing Carplay navigation apps. Unless they accept it so long as it requires iOS 12 to work, but the app store won't take iOS 12 apps until it's released. So.....

Yeah, they do actually.

Find more information here: https://support.google.com/waze/beta/answer/7287364?hl=en&ref_topic=7287566&visit_id=1-636638312512190154-3572480666&rd=1