This recipe uses 1 pound of ground beef, but you can absolutely use 2 pounds of ground beef and double the other ingredients. In order to achieve the same great outcome as in this recipe, I would keep the air fryer temperature the same and cook for an additional 15-20 minutes. You shouldn't need to double the timing because, once meat reaches a certain internal temperature, the internal temperature rises more quickly. The best way to know if your meatloaf is done is by checking with an instant read thermometer to make sure the internal temperature reaches 165℉/74℃. I usually take my meatloaf out once it reaches 160℉/71℃ to account for carry-over cooking which will bring the meatloaf up by 5-15°. The shape and temperature of your meatloaf will also play a role in how long it takes to cook, so I always recommend cooking to temperature and not time.