I recently got hold of an iPad Air 2 that was sitting in a drawer. Had it recharged, seems to hold the charge. However it has iOS 9.3.1 and it says it cannot upgrade to 13 over the wire.
It requires iTunes and a computer. I also have a MacBook Pro (2014) running Mojave (10.14.6) so I fired up iTunes and connected the iPad via a USB cable.
The iTunes app sees the iPad and recommends upgrading to iOS 13. It asks me if I want backup. Nothing valuable on the iPad so I continue without backup. The iPad locks suddenly (no timeout). Then iTunes app (on Mac) asks me to type the unlock code on the iPad in order to continue. I do that and the iPad unlocks.
Then nothing happens. Neither on the Mac nor on the iPad.
Will provide any other information as necessary. Let me know in the comments.