Creating a building game, need suggestions an an optimal approach

I am developing a game where automatons gradually construct a multilevel building in real-time. The building needs to be fairly dynamic, block by block. Not at a voxel level like Minecraft, but not just a bunch of large premade pieces. The building itself does not need realistic physics, but does need collision. I am very wary of creating thousands and thousands of objects for my building, especially as it gets larger. What kind of objects or approaches could you suggest? Is it possible for hundreds of objects created individually to be reduced later in the game to a single mesh or something else more efficient? Is something like this even possible within Unreal or would I be best served with a different engine? Thanks for any advice offered!