Writing just to correct the answer provided here.
We have dozens of Dell Latitude 7280 (exact model) in our company, they support power delivery.
Also the non thunderbolt version with core i5 they do.
Indeed the Dell WD15 docking station that comes with it (in our specific desk setup), allows to run all the operation with a single USB C w/ displayport cable. That's the only thing that runs from the computer, it both powers the computer, provides video output to the dell display through displayport cable of the docking station, and connects any other docked peripheral.