2020 iMac can be sold?

If you are asking can you provide this iMac as a trade-in towards the purchase of a new Mac, then you simply just need to start the ordering process for the new Mac from the Apple online store. One of the first steps will ask you if you have a Mac to trade-in. Just answer a few questions, and you will be provided with an estimated trade-in value. You can then decide if it is worth it, or not, to you to do so.

This is an apple users forum, we are not apple and apple is not participating here so we cannot give you any information about trade ins.

Make sure to never share your serial number online as that is privacy sensitive information