No, you have to file a separate tax return for each year. You cannot combine them.

You cannot use TurboTax Online to file for 2019. TurboTax Online is only for the current tax year, which is now 2020. To file for 2019 you have to use the CD or download TurboTax software for 2019. You can purchase a download at the following link. There is no free filing for past years.

Past Years' Products

You might get a better price from a reputable online seller that still has TurboTax for 2019 in stock.

Tax returns for past years cannot be e-filed. You will have to print your 2019 tax return, sign it, and file it by mail.

No, you need to file for each tax year on a separate tax return. 

Yes, you can file a 2019 tax return AND a 2020 tax return both in 2021.

 Link to TurboTax 2019

Can I file 2020 with 2021 since 2020 was rejected?

@Shir1 No.   If your 2020 return was rejected --you cannot e-file it.   Most rejections were for incorrect AGI.   A 2020 return can only be filed by mail now.   Print it, sign it in ink and mail it in.    You cannot combine it in any way at all with your 2021 return.

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.

Federal and state returns must be in separate envelopes and they are mailed to different addresses.  Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.