On standard WL74, you can add a Trailer-tow package to all trim levels except Trailhawk. It adds a Class IV hitch receiver and four- and seven-pin wiring harness. On Laredo and Limited, the tow package also adds rear load-leveling suspension and a full-size spare tire; the last two items are already standard on Overland and Summit 4x4 models. (The docs seem to be saying that the last two items can’t be added to Overland or Summit 2x4 models, but it may just be written poorly.) I don’t see anything about improved cooling.
On 4xe, the tow package (with all the same items) is an option for Limited and standard for Trailhawk, Overland, and Summit.