Sorry Online is only for 2020 now.
To do a prior year return you have to buy the Desktop program here,
You will need a full Windows or Mac to install it on.
If you want to file for free you can fill out the forms by hand. Here are some basic forms.....
Here is the 2019 1040 return
or if you want bigger type use 1040SR for Seniors,
2019 Instructions https://www.irs.gov/pub/irs-prior/i1040gi--2019.pdf
2019 EIC and Tax Tables https://www.irs.gov/pub/irs-prior/i1040tt--2019.pdf
2019 Schedules 1-3
Don’t forget your state. And you will have to print and mail your returns. So be sure to attach copies of your W2s and any 1099s that have withholding on them. You have to mail federal and state in separate envelopes because they go to different places. Get a tracking number from the post office when you mail them for proof of filing.
FYI - Then when you file 2020 next year you will need to enter 0 zero for the 2019 AGI since you are filing 2019 late.
The free versions always end on Oct 15. 2019 can only be done with TurboTax now with the desktop software installed on a Mac or Windows computer. You can download blank form from the IRS and manually fill them out for free.