Apple Stores will NOT take trade-ins due to COVID. But online order system says they will.

You can set up a trade-in while placing an order for a new device online or you can use the following site to do a trade-in without ordering a new device. See information on both in the following (and be sure to see the FAQ section): https://www.apple.com/shop/trade-in

third party companies/partners are handling the process. You will get an initial estimated value from Apple, but the final offer will not come until after the company examines the device. You can then accept the offer or not.