To complete and file a 2019 thru 2021 tax return using TurboTax you would need to purchase, download and install on a personal computer one of the desktop editions for each tax year from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
A prior year tax return can only be printed and mailed, it cannot be e-filed. Use separate envelopes when mailing multiple tax years.