In blockchain.com trading account which is the topic of discussion here, you can withdraw your fund to any address you want directly without any need to moving the fund to another account or your main wallet.
It's good to know that for informational purposes. I am not familiar with the way Blockchain.com functions and how their internal wallets are set up. But from n0nce's post, I felt like he was looking for information about exchanges in general. Not specifically the systems deployed by Blockchain.com.