The 3+2 program does not end in a master’s from Columbia; it ends in two bachelor’s degrees: one from URichmond in something (maybe physics), and one from Columbia in engineering. URichmond does have a 3-1-1 program for exceptionally well-prepared students who do 3 years at URichmond, 1 year at the partner institution to finish the BA, and then - if your fourth year work is “of good quality” - 1 year to do an accelerated master’s degree at the partner institution. It’s unclear whether they have this arrangement with Columbia and how well you have to do in your fourth year in order to be admitted to the accelerated master’s. You would probably have to complete some graduate-level work in your fourth year.
They also have a 4-2 program which is 4 years at Richmond plus 2 years at Columbia, but that one is competitive whereas the 3/2 program is guaranteed.