Disable Volume and Power button screenshot Pressing Volume (-Up or -Down) and Power button takes automatic screenshot. 
Can I disable this feature? 
(I often grab my phone and press those buttons by mistake).

I use OnePlus with OxygenOS 9.
For the moment, you unfortunately can't unless your phone is rooted. A user submitted a suggestion to have Option to disable screenshot using volume down and power button for OnePlus 6T. On the same thread, there are also owners of other OnePlus models asking for the same. 

If your phone is rooted, you can disable the package com.oneplus.screenshot although it will introduce the disadvantage of no longer being able to take screentshots.

You can also try to remap the keys as shown here.