I think this will only be done during the developer and public beta phaseI was wondering the same thing
I say that as it seems like the same kind of thing was done this time two years ago for the initial release of Apple Intelligence, but then ever since after that whenever you set up a new iPhone that supports it, it seemingly will download those assets right away instead of making us wait like this right now
I suspect this will be the same case for Siri once iOS 27 gets to its final release come the fall when the new iPhones come out, even though it's been rumored that even once iOS 27 does come out, at least for some time, just like Apple Intelligence, it will have a beta label on it