Do not try and amend the 2020 tax return since the Form 1040-X has not been finalized.
The IRS Form 1040-X for amending a 2020 tax return is scheduled to be available on 03/25/2021 (subject to change)
See this TurboTax support FAQ for information for the unemployment compensation exclusion - https://ttlc.intuit.com/community/tax-topics/help/how-do-i-claim-the-new-unemployment-benefits-in-tu...
Also see this IRS statement - https://www.irs.gov/newsroom/irs-statement-american-rescue-plan-act-of-2021
