How can I access a set of prefabricated rooms at runtime?

I have a list of prefabricated rooms of different set dimensions. For example rooms that are 3x3, 4x2, etc. I would like to be able to access them at runtime to create dungeons. The algorithm that I’m using requires that I be able to modify them slightly by changing the positions of the doors based upon how they connect to the different rooms.

My thought is to create a map from room dimensions to a list of rooms that meet that criteria. How can I create the list of prefabricated rooms in unreal and be able to use them using c++?

Note: this is a personal project designed to learn how to program in unreal using c++, so I don’t want to use plug-in solutions.

Thanks!