Give me your address and I'll send you enough ETH to make the transaction.

Login blockchain.com ---> Settings ---> Security -----> Backup Recovery Phrase -----> write it down (Keep it safe.)
Click --->  https://metamask.io/  ---> Metamask extension  ---->Add to Chrome ----> Click on the MetaMask icon ---> Import using account seed phrase. enter that seed ---> strong password.
I have tried to make things as simple as possible.

Next time stay away from blockchain.com wallet

Is your usdt erc20?
Can you see your address and the usdt in etherscan?

You can easily recover your funds in any ethereum wallet using your 12 words, if you can see the balance in etherscan.

I suggest that you download the metamask extension (chrome or Firefox or brave browser).
Just insert your 12 words and the contract address of usst (which you can see in etherscan)