You cannot file an extension for tax year 2020.
You can file a 2020 tax return but you will have to purchase and download one of the 2020 desktop editions. The TurboTax online editions are only for tax year 2021.
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.
