I recieved my first stimulus but not my second. I have already filed my 2020 taxes. Was advised after the fact there was a process I could have done while filing so I could have recieved my 2nd stimul

As long as you qualify, you can still receive your second stimulus amount.  TurboTax has established a procedure for taxpayers with this type of situation. 

Please see the TurboTax Help article I've already claimed the Recovery Rebate Credit. How can I review and update my 2020 tax return? or I didn't claim the Recovery Rebate Credit. How do I review and update my 2020 tax return?, as appropriate, for guidance.

If you haven’t received all of your stimulus yet, you can claim it in your 2020 tax refund.

Thank you for responding.