It is too late to file an extension, an extension needed to be filed by July 15, 2020. If you are due a refund there is no penalty for filing a late return. If you owe taxes, they were due by July 15th to avoid a penalty & interest. You should pay taxes owed as soon as possible.
You can pay online on the IRS website for Federal taxes owed, and on your State's website for State taxes owed.