I don't know why it was not accepting 10/15 and telling you 10/16 if your computer clock and date settings were correct, and correct time zone for 10/15/2019.
In any case did you successfully submit the efile? Efile is still open at the IRS, so it should not be rejected strictly because it was efiled on 10/16/2019. A lot of people efile late returns. If it's rejected, it would likely be for some other reason. The problem would be that TurboTax may no longer let one efile for the first time after October 15; i.e., efiling may have shut down for an unfiled return. I'm trying to get TurboTax folks to verify that in regards to the desktop software.
If you did let you submit the file, what status is showing now with this efile status check tool? Does it say pending, accepted, rejected, etc.?
If you are using desktop software, you can (and should) also check the efile status from within your desktop program. When you launch the program and open the return, it may automatically prompt you to check the efile status. Or you can open your return, than go to the top left corner of the interface and in the top menubar click on the FILE menu, then in the dropdown menu choose ELECTRONIC FILING, then in the next menu "Check Electronic Filing Status."
If you are getting a Federal refund, there is no penalty for a late Federal return.
If you owed Federal taxes and receive a late filing penalty, you may be able to ask the IRS for it to be abated. There is a procedure to request such, especially for a first-time penalty, and you can explain to the IRS what happened.