Using Sub-levels For Random Generation

I’m trying to make a randomly generated world. That can load and unload chunks based on where the player is. What I’m attempting to do is using C++ make it so that I make a new World and add it to the persistent level. I have had no luck with this method. 1: is this possible. If so how, I’ve been trying for two days. 2: is there a better way to generate a city full of taller buildings and dynamically load every floor. Any help would be appreciated, c++ or blueprints I don’t care. Also currently i have an actor that spawn the world/buildings, an actor that spawns the building with X amount of floors, and an actor to generate the floor itself.