Spatial Relationship??

Is there a term for the ability to look at a set of objects of various shapes and sizes and select a larger container and have all the smaller ones fit in without loads of left over space?

Do you mean packing problems?

Yes! Exactly. Is there a name for a person who excels at “packaging problems”?

Someone who does it in the mundane sense is a packer.

People studying it as a theoretical science are, I guess, mathematicians, geometricians and topologists, for a start.