If the 11 is a pro max, send it brother. Save your money and buy it. Many will argue that 11 won’t get the next iOS which it probably won’t but there upgrades in the last 5 years have been marginal at best. 11 pro max, here and battery is still good for a day and half, still snappy performance.
Assume everything you are told from the moment you walk into the dealership to the second you leave us a complete fabrication. There is literally nothing these guys and women won’t do to make a sale.