This is a home design. I intially created the whole thing in unreal because i wanted to test if using preexisting models of unreal can give me a advantage in terms of game perfomance .. and yes it does. But later i imported the whole Unreal map in blender did some modification and drafted final output.

The reason creating a map in unreal is helpful is because even though this map have same cube used different places they all have same primary mesh so it doesnt load multiple asset in unreal game memory and use single asset difference refrences.....you can check this in blender too- when you edit a wall in my project using edit mode it impacts all the other walls of map.