Is UE4 able to load external level file?

Hi, I am newbie to UE4.
Can UE4 load external levels (i.e. created by someone else who does not have source of my project) like a file?
I am making racing-like game, so, only few logic wanted to be used like moving trees, falling stones when passing through some checkpoints, flashing lights etc, so no logic almost.

I want to make a tiny browser to select map and to load it.

Please give some references to search for.