The Microsoft Lumia 650 XL was never released, but numerous leaks have been revealed to the public with some claiming it's the Lumia 650 XL and some it's the Lumia 850. The cancelled release of the phone didn't stop hacker Calyx Hikari from successfully running Windows RT 8.1 PE on the device.
The video below (via WBitalia) clearly shows the device and the software (we recommend that you mute the video):
Aside from the software, this video shows one of the models of the Lumia 650 XL, in this case the RM-1157, that only has one SIM-slot and a non-removable battery. Otherwise, it seems like a bigger version of the Lumia 650, and that is exactly what it should be.