You don't have to do anything. If you are eligible for the unemployment exclusion the IRS will recalculate your tax return and send you the additional refund. It might be a couple of months before you get it. For more information see the following IRS announcements and FAQ.
IRS to recalculate taxes on unemployment benefits; refunds to start in May
IRS begins correcting tax returns for unemployment compensation income exclusion
IRS continues unemployment compensation adjustments, prepares another 1.5 million refunds
2020 Unemployment Compensation Exclusion FAQs
The law changed on March 11, 2021. If you filed your return before March 15, then you overpaid and will receive an adjustment from the IRS. If you filed after March 15, 2021 the adjustment was applied and you did not overpay. I may be a few days off on when TurboTax made the change, but remember it being very quickly after the law was changed.