Hi Vanslash,
With the old layer system I believe it was ‘editor only’ (as in you could only do operations on it while in editor and not in game)
There’s a new system called Data Layers that might help you achieve what you’re after. (Be sure to look at ‘Using Data Layers with Blueprints’ section of that doc)
Also, for a ‘real-world’ example I know that Data Layers were used to switch between light and dark worlds in the Valley of the Ancient sample.
Another approach would be to load/unload levels with level streaming. Edit: Level Streaming is not Compatible with world partition.
Hope that helps!