Unfortunately, you cannot flat tow a Kia Sportage under any circumstances. If you flat tow the Sportage, you can damage the drivetrain and transmission, as well as have your warranty voided. On top of that, any damage is likely to be denied by your insurer because you were towing the vehicle improperly.
Fortunately, you can still tow the Kia Sportage through other means. You can use a two-wheel dolly to flat tow the front-wheel-drive version, as long as the front wheels are off the ground. Both the front-wheel-drive and all-wheel-drive versions can be towed on a flatbed trailer, so you always have that option.