Unfortunately, you cannot flat tow any trim or drivetrain of the 2019 GMC Terrain. Flat towing this model can significantly damage the transmission and drivetrain, so avoid this towing method unless you want a hefty repair bill.
If you have to tow your Terrain, you still have two options. If you have an AWD Terrain, you must use a flatbed trailer. However, you can tow a front-wheel-drive Terrain with a two-wheel dolly. Just make sure that your front wheels are lifted off the ground.
For more information about towing your GMC Terrain, check out pages 363 through 365 of your 2019 GMC Terrain owner’s manual.