I filed my 2019 taxes but still need to file for 2018. Is there a free app?

[DoninGA]

No, there is not a free application for a prior year tax return.

To complete and file a 2018 tax return using TurboTax you would need to purchase, download and install on a personal computer one of the 2018 desktop editions from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/

A 2018 tax return can only be printed and mailed, it cannot be e-filed.