For Cintiq pro and Mobile Studio pro user on Windows, this is how to improve accuracy of calibration by 100%. Panel property of the tablet will look shrunk but it’s fine you can use it. For the cintiq pro 16 I highly recommend to not go 4K with the adapter it screws up the calibration, so you should stay in 2K. But if you have USB-C port it is fine.
For mac user, you don’t need to do anything, but I highly recommend to stay 2K with the adapter with the cintiq pro 16 if you don’t have USB-C, even though the calibration works properly at 4K you’ll have some issue with how the cursor react (it will compute as a 2K display while you have 4K...)