TurboTax does not support tax year 2019.
You can use the IRS website to manually complete and then print the Form 1040-X for mailing.
Go to this website for the 2019 Form 1040-X -https://www.irs.gov/pub/irs-prior/f1040x--2019.pdf
Go to this website for the 2019 Form 1040-X instructions - https://www.irs.gov/pub/irs-prior/i1040x--2019.pdf
IRS website for mailing the amended return, by state, with an without a tax payment - https://www.irs.gov/filing/where-to-file-paper-tax-returns-with-or-without-a-payment
