Possible but not easy - it is better to amend with H&R since they have the 2019 as a starting point.
To use TurboTax you will need to purchase the 2019 software and duplicate the 2019 *exactally* as it was filed with H&R, print for filing to fool TurboTax that you mail filed it, then you could amend.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**