To complete and file a 2020 tax return using TurboTax you would need to purchase, download and install on a personal computer one of the 2020 desktop editions from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
A 2020 tax return can only be printed and mailed, it cannot be e-filed.
If you want to file for free you can fill out the forms by hand. Here are some basic forms…..
Here is the IRS 2020 Form 1040
https://www.irs.gov/pub/irs-prior/f1040--2020.pdf
or if you want bigger type use 1040SR for Seniors,
https://www.irs.gov/pub/irs-pdf/f1040s.pdf
And 2020 Instructions
https://www.irs.gov/pub/irs-pdf/i1040gi.pdf
2020 Tax and EIC Tables
https://www.irs.gov/pub/irs-pdf/i1040tt.pdf
Sch 1 : https://www.irs.gov/pub/irs-pdf/f1040s1.pdf
Sch 2 : https://www.irs.gov/pub/irs-pdf/f1040s2.pdf
Sch 3 : https://www.irs.gov/pub/irs-pdf/f1040s3.pdf
Then when you do file 2021 enter 0 for the 2020 AGI since you are filing 2020 late.
You have to print and mail prior year returns. When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS received the return. Don’t forget state.
