No. There are no second extensions. If you do not file by October 15 then you are just late. And you will not be able to e-file. E-filing will close down after that deadline so if you miss it, you have to print sign and mail your tax return instead. And if you have been using online TT you will end up having to purchase and download desktop software to a full PC or Mac in order to change or finish your incomplete 2019 return.
If you are getting a refund, there is not a penalty for filing past the deadline. If you owe taxes, the interest/penalties will be calculated by the IRS based on how much you owe and when they receive your return and payment. The IRS will bill you for this; it will not be calculated by TurboTax.