The 1040SR is the same as the regular 1040 just larger type and the Standard Deduction chart is added to the bottom of page 1. But it has the same line numbers. You automatically get the SR if you or your spouse is 65 or older. If you really want to use the regular 1040 in the Online version, you can print your return and copy the amounts into a blank 1040 (link below) from the 1040SR.
If you are using the Desktop program there is a way to force the one you want, switch to Forms and the Info Wks part II has a selection for 1040 or 1040SR. If you look at it in Forms Mode it shows the 1040 but if you print it out it will be the 1040SR.
Even the regular 2019 1040 return is now different than 2018. They changed the line numbers again and reduced the schedules from 6 to 3.
You can compare them,
2018 1040 https://www.irs.gov/pub/irs-prior/f1040--2018.pdf
2019 1040 https://www.irs.gov/pub/irs-pdf/f1040.pdf
2019 1040SR https://www.irs.gov/pub/irs-pdf/f1040s.pdf
