At its most basic level, all you need for a map to wrap around is to have anything that goes past one edge of the map show up on the other side. If the position of something on the map is a set of coordinates, from, say, -100 to 100, going past 100 just wraps you around to -100. The graphics do the same thing, so if the camera is looking across the boundary, it shows stuff on both sides.

You can fake this by having visual duplicates of the map placed at the edges, and teleport anything that crosses to the opposite coordinates, but you have to be careful that this doesn't mess with the physics.

Unreal isn't really designed for dynamic map manipulation, so you may have to write some of this stuff yourself to handle the edge cases. It might be easiest to chunk the entire map into sections larger than the maximum camera viewing area, and then dynamically arrange where they are in space. (Ideally, this would only be changing their visual representation, and not their underlying representation in the physics.)

Here's an article that talks about some games that do this: http://simonschreibt.de/gat/1nsane-carpet-2-repetitive-worlds/