Question help

You may also read this ---> https://www.apple.com/shop/trade-in

If you buy an iPhone, iPad, Mac, or Apple Watch and pay in full, they’ll apply a refund to your original payment method up to the total purchase price. For any remaining amount, you’ll receive an Apple Store Gift Card via email.

If you buy an iPhone using Apple iPhone Payments, your estimated trade-in credit will be applied directly to the purchase of your new iPhone. Once they receive your trade-in device and confirm that the condition matches what you described, there’s nothing more you need to do. If it doesn’t match, your original payment method will be charged the difference in value. In that case, they’ll work with you to confirm that you still want to move forward with the trade-in.

Who do you owe?

If you owe Apple anything you will need to pay before they'll take it in for trade.

If you owe your carrier, then, Apple will likely take it, and offer you some value for it you can use towards the purchase of an XR, but it will not be a straight trade. The XR is more expensive than the 8, and you will need to cover the difference.

Also, if you owe your carrier, and trade it in to Apple, you would still need to pay your carrier whatever you owe.

Who do you owe the $280 to? If your carrier, you’ll need to pay the balance off first as technically, you would not actually own the property you’re trading in.