It is not possible to e-file a prior year tax return. The IRS Says so. Additionally, e-filing for the 2019 tax filing season was closed by the IRS on Oct 31, 2020. You have no choice but to print, sign and mail the return now.
It is also not possible to prepare a tax return for 2019 or before with the online version of TurboTax. That too has been shut down permanently and forever. It will not open again for the 2020 tax filing season until mid December 2020 at the earliest, so you can start preparing your 2020 tax return.
