I just installed fog lights on my 2016 fusion se, was not equipped with factory installed fog lights. I just purchased a fog light kit.
Then purchased wiring harness: dg9z-15k867-b
and switch part # dg9z-11654-ba
Took off front bumper, put in fog lights, switched wiring harnesses, put bumper back on, installed new headlight switch.
Did nothing else, took a couple of hours. Work great.