Ipads could come with their own version of 12.0.1 that has Face ID enabled for them.probably one more beta at the most. the new ipad models are being released rather soon and will need to have 12.1 already on them when sent out. 12.0 wont work on the new ipads because of face ID not being enabled till 12.1 supposedly and they would not ship new ipads with that feature not working among other features that are not enabled till 12.1.
i just read iphone XR reviews and they said the device comes with 12.0.1 so we can put that to rest that they would ship with 12.1
Anyway, 12.1 is most logical.
Also, just because new iPads are being presented on the 30th doesn’t mean they will be ready to ship same week or so. They could be held for delivery several weeks later, which I guess will be the case (late November).