I have had both. My 2017 Lariat had an Amp Reasearch bumper mounded step. It worked great, no issues getting in and out of bed. My 2021 has a built in step. It is very nice and really easy access t the bed. They both work great.
I have a 2021 F150 King Ranch with max tow. It came with a sensor and a cable. The sensor mounts on the frame of the trailer and connects to the truck. From what I have read (i have not tried it) once the sensor is connected and you perform a few maneuvers the truck will figure out the length...