However... In November i will get my iPhone XS Plus/Max or however the name will be. Does the iCloud backup only has the installed app and it’s files or also the saved analytic data’s?
Ok, so before getting your new iPhone in November you can leave the beta program as soon as iOS 12 is released to the general public. Then you back up your current iPhone to the iCloud, as usual. Once you get the new iPhone, provided you do not have too much stuff to copy over, you can just pull that iCloud backed up data OTA.