While exploring the Setup app in iOS 12, 9to5Mac discovered an identifier referring to an iPad labeled "iPad2018Fall". The identifier also added to a bevy of evidence and reports suggesting a new iPad Pro model is imminent.
That's not the only hint about new iPads in the iOS 12.1 beta, though. First of all, 9to5Mac found a daemon running in iOS 12.1 that seems to suggest support for syncing Memojis across iOS devices. While some people do have multiple iPhones, not many do, and syncing like this most often helps users keep things squared between an iPhone and an iPad. Today's iPads don't support Memojis, but tomorrow's might.
Further, developer Steve Troughton-Smith noted on Twitter that iOS 12.1 appears to include support for Face ID in landscape orientation. This would not be possible with existing iPhone hardware, suggesting that it might be coming in a future iPad with Face ID. He also pointed out an option for a virtualized 4K external display for the iPad Pro in Apple's iOS simulator. This lends support to an analyst report that the iPad Pro would use USB-C, not Lightning, as its primary port. That is still far from certain, though.