Yes it is OnStartTouch > !activator > SetFogController > [name of env_fog_controller entity] but the text appears red because there's no "!activator" entity and no "SetFogController" input and I'm not sure if it will workIs this how 2fort does it and have you checked its decompiled version? I don't believe 2fort does it like this but I might recall incorrectly.
I thought it was: Use OnStartTouch > !activator > SetFogController > [name of env_fog_controller entity]