Unfortunately, no model year or trim of the Toyota 4Runner is designed for flat towing. If you flat tow either the 2WD or 4WD versions of the Toyota 4Runner, you risk damaging the transmission, drivetrain, and other mechanical components.
That said, you can certainly still tow the Toyota 4Runner when you head to the off-road track. If you have a 4WD 4Runner, you must use a flatbed trailer. However, you can tow the 2WD version with either a flatbed or a two-wheel dolly. If you use a two-wheel dolly, note that you must tow it with the rear wheels lifted and the front wheels on the ground, as doing the opposite could damage the drivetrain.