Some folks can do work themselves and add options that were not available originally. Perhaps the OP was seeking information to get a handle on what can be done, as he said. The first step would be checking availability, which sounds like what he's trying to do.
The limiting factor here would be the "clockspring" that carries power from the steering column to the wheel. All the 3rd Gens share the same one, I believe, which has a bunch of terminals to provide transfer of radio and heater controls, horn and cruise control circuits to the steering wheel. While many cars don't use all the conductors, they are all low amperage, so they probably wouldn't carry the load for the heater on a 2018 heated wheel. The OP can check this all out of course by comparing the wiring diagrams of a 2018 vs 2017 and compare the wire gauge for the heater harness vs the available leads on an earlier clockspring. He could then compare part numbers for heater vs non-heated clocksprings, Gen 3 vs Gen 4 cars.
Now if anyone had a heater on his 3rd Gen Expedition, the research would have been done for him. That information would be more helpful to the lad than a string on insulting remarks based on information gleaned from a Google search.
