Yesterday Apple dropped the first iOS 12.1 beta release, and hidden inside the update's code may be a hint at a new iPad model.
A new identified found in iOS 12.1 appears to suggest that a new iPad model is coming later this year. 9to5Mac notes that in the assets used by the Setup app, which runs when you set up a new device, there's a string that includes the phrase "iPad2018Fall". You can see it below.
There are no other details about this device included in the bit of code, but this string is still notable because Apple hasn't said anything about launching new iPads later this year. Rumors have suggested that Apple is prepping a new iPad Pro model with slimmer bezels and Face ID unlock. Other code found in iOS 12.1 suggests that Face ID has support for landscape orientation, likely for use with a new iPad.
If Apple is planning to launch a new iPad this year, it's possible that an announcement could come sometime in October. That timing would give Apple some space after its recent iPhone event, but would likely still give it enough time to get the new iPad out by the holidays.
Face ID has support for landscape orientation (presumably for iPad only), and iOS 12.1 seems to care a lot more about whether an external display is connected (perhaps due to iPad USB-C rumors; it won't have the Lighting HDMI adapter as an intermediary for video-out)
— Steve Troughton-Smith (@stroughtonsmith) September 18, 2018