Sell to specific user

How can I place an offering and reserve it for a specific user like in open sea

The question is how to do it in your own smart contract/application?

Yes, sorry, I couldnโ€™t find any documentation on this and I want to know if itโ€™s possible.

If you make your own smart contract than you can put all the rules that you want in that smart contract.

Do you have any references or example of this?

Maybe you can find the source code of the contract for what opensea uses.

It should be easy to set a variable to an address and to check that variable in a function. The sell part seems more complicated.