I want to change iPhone 13 blue 128 GB to 256GG

If you purchased it online from Apple, you will need to contact the online store to setup a return. Use the Get Support link at the top of the page. If you purchased it at an Apple retail store, then return to the store and you can return it there. After the return and refund, you will be able to purchase a new device of your choosing, if they have it in stock.

If you purchased the device from Apple less than 14 days ago, you can return it for a refund and then purchase a new phone. If it has been more than 14 days, you would need to sell the phone on your own, and then use that money along with additional funds to purchase the new phone. You cannot trade-in a new device.

If you purchased the iPhone less than 14 days ago, then you can return your iPhone for a full refund. After that, you can purchase the model that you want. I am basing that on what is true in the US. If more than 14 days have elapsed since the purchase, then you own the Blue iPhone 13 and will not be able to exchange/return it.

Axel F.

Actually, Apple has already implemented the Holiday return policy for 2021:

Items purchased at the Apple Online Store that are received between November 1, 2021 and December 25, 2021, may be returned through January 8, 2022. Please note that all other terms and conditions provided in the Apple Online Store Sales and Refunds Policy are still applicable with respect to such items purchased. All purchases made after December 25, 2021 are subject to the Standard Return Policy.

You are right LG. And, I should have known. I just purchased an iPhone 13 Pro Max and was made aware of the Holiday Return Policy. Thanks for shedding light on this.

Axel F.