iPad pro

You cannot change the screen refresh rate in any iPad Pro that has the 120 Hz refresh rate.

This capability is built into the iPad’s screen hardware and the iPad’s firmware.

There are no settings to change this screen refresh rate.

There is nothing in the technical specs for the 2018 iPad Pro that identifies refresh rate, however, I found this link in another post, iPad Pro, in 10.5-inch and 12.9-inch models, introduces the world’s most advanced display and breakthrough performance - Apple and it shows up to 120Hz and I do not see any setting in my iPad Pro 11 that allows for making any adjustments.