I followed the instructions to amend my 2019 returns. However, it doesn't show the option for efile

[Critter-3]

The option to download the amendment program is not available at this time while they are archiving the 2019 returns ... so if you don't want to wait until December then contact TT support to get a download pushed your way. 

Use this phone number and select TurboTax - 1-800-4-INTUIT (1-800-446-8848)

Or –

Use this website to contact TurboTax support during business hours - https://support.turbotax.intuit.com/contact/

Or –

Support can also be reached by messaging them on these pages https://www.facebook.com/turbotax/ and https://twitter.com/TeamTurboTax

[Nishi2008]

We waited - until January 22, 2021 and tried to amend the 2019 return. We still do not see the e-file option, and are getting this message: To file your amended returns, you’ll need to print and mail them

[DaraLO]

@Nishi2008 Amendments cannot be e-filed. If you're amending a 2019 return you originally prepared in TurboTax Online, you can amend it online by signing into your account.  However, you will need to print and mail your return to the IRS.

Reference:  How do I amend my 2019 TurboTax Online return?

[VolvoGirl]

There was a small window that you could efile a 2019 Amended return from Aug 26 to Oct 15 before all Efiling closed.  We don't  know if you can efile Amended returns again when Efiling opens for 2020 on Feb 12 or later.  It's all new.