I want to sell my iPhone XR

ok so as ckuan said, you cannot sell here or anything but i believe your asking how much apple will take for your phone and it's ~$270 (as seen in https://www.apple.com/shop/trade-in ) if it's in good condition (also bear in mind you don't have to give it to apple, eBay does exist, just be careful on there and make sure find my iPhone is disabled, you sign out of iCloud, all that stuff, make sure the person your selling it to can't get your data), if you have any other questions or something feel free to ask

That is not a technical question.

This is not a market place.