As Vinn says, that was a transitional time for Model X tow package.
I ordered the smaller accessory hitch, but when it arrived it had the full size hitch installed. The hardware was installed with hitch, receiver and plugs, but the software was not enabled.
About 6 months later I took it into service for a folding seat concern. They were able to install the Software (no charge
and now it automatically senses when I am towing something and switches to tow mode. Have used it to carry bikes and a small accessory carry all tray.
It pulls fantastic, with lots of power, but you need to always be careful not to overload the ball or receiver. There was a small hatch below the rear bumper. Took it off and all the stuff was already installed.
At that time many owners asked to have the hitch installed after delivery, but were told it was a difficult thing to do. Some got it done, but soon afterwards the Service centers were advised to discontinue installing hitches on cars that did not come from the factory with the hardware.
Hitch gives tremendous versatiility to the Model X.