I have a map and I want all areas outside of a point lights radius to be pitch black, but I can’t seem to do it, I was wondering if post processing could be used to fix this or some other tool.
You could play with eye adaptation(auto exposure) settings in post process to darken the non-lit environment as dark as possible i think.
Why dont you just start a blank map + add a point light? 
-> the area around the point light is lit by the light and everything else is black
I don’t think that this would work as when you nether area around the light and raise the exposure you are going to see everything not just the stuff that is inside the zone with you. What he is talking about is having no other lights except a single dynamic point light that need to have a decay to it so that it only lights objects within that decay radius.
Pitch black as in someone turned off the TV pitch black?
Assuming that no lighting solution will be projected into this area period you could try and make a wall object where you want the black to begin and give it a completely black material.
I’m wanting to do the exact same thing!
I’m not sure I understand this correctly, but in World Settings for the level, under Lightmass -> Lightmass Settings, setting the Environment Color to black makes things dark. And outside the radius of a light, there isn’t anything.