No. You cannot enter a 2019 W-2 on a 2020 tax return.
You will have to amend the 2019 tax return that was filed to add the 2019 W-2.
See this TurboTax support FAQ for amending a 2019 tax return - https://ttlc.intuit.com/community/tax-topics/help/how-do-i-amend-a-2019-return-in-turbotax/01/123845...
