When can I get my 2020 tax return. I just received my w2

Did you already file your 2019 tax return?  Is the W-2 you received for 2019?

If you have filed the 2019 tax return and have received a 2019 W-2, then you will have to amend the 2019 tax return that was filed to add the W-2.

An 2019 amended tax return, Form 1040X, can only be printed, signed, dated and mailed by you to the IRS,  or it can be e-filed. The IRS will take up to 4 months to process the amended tax return. Wait until you have received the tax refund or the taxes owed have been paid and processed by the IRS before amending the tax return.

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/01/1238456

A 2020 tax return cannot be filed until after 12/31/2020.  Employers cannot issue 2020 W-2's until after 12/31/20202.