You can indicate an OCIO config file in the details of your nDisplay config.
However, first you need to create an OCIO config by right clicking in content browser and Misc > Open Color IO Config
Open the config and browse to the file. You should then set up the arrays for your sources and outputs in the config.
More info is found in the Unreal Documentation:
https://dev.epicgames.com/documentation/en-us/unreal-engine/opencolorio-quick-start-for-unreal-engine?application_version=5.4