The Social Security benefits received are on the federal tax return Form 1040 Line 6a with any taxable amount on Line 6b.
If you did not enter the SSA-1099 on the tax return then you will have to amend the 2020 tax return that was filed.
An amended return, Form 1040X, can only be printed and mailed to the IRS if the original tax return was not e-filed. The IRS will take up to 16 weeks or longer to process an amended tax return.
Before starting to amend the tax return, wait for the tax refund to be received or the taxes due to be paid and processed by the IRS.
See this TurboTax support FAQ on amending a tax return originally completed and filed using the 2020 TurboTax editions - https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-return/01/27439
Did you enter it? It might not be taxable. Only up to 85% is taxable depending on your other income. Check 1040 line 6a and 6b for it.
If you did not enter it at all then wait for your original return to finish processing and you get the refund or pay the tax due. Then you can amend.
How to amend a 2020 return