How to reorder app pages?

You can't do entire pages on an iOS device, you can only do apps or folders individually.

RE downloading the apple configurator - it’s no longer available

Yes it is, but you have to look where I said to look i.e. Mac App Store

You can do it directly on the phone, or use Apple Configurator from the Mac App Store, or install iTunes 12.6.3 instead, or go back to an earlier (pre-12.7) version.