Thanks @Bill.French, but this itself does not help. I do not want to sort by a field, but by the accuracy of the match. So if I have to records, where record A has just the element “First” selected in the column and the record B has both “First” and “Second” selected, I want to sort the results, so that record B comes before record A.
@Bill.French tends to do a lot of work with the REST API, so he tends to think in those terms. However, I think that @Tom_Muller is asking for a simple formula field for sorting within the regular interface.
Have your formula return a value that says how accurate the match is.