Is it possible to claim Savers Credit for 2020/2019 tax returns since I didn't realize I could do it? And if yes, What are the steps to do it?

You would have to file amended returns for 2019 and 2020 to add the Savers Credit.

See the following FAQ for instructions to amend tax returns that you filed with TurboTax.

How to amend (change or correct) a return you've already filed

An amended return has to be filed on a special form, Form 1040-X. Don't file the amended return until your first return has been accepted and you have received the original refund.