The deadline for filing an extension was on July 15. You should file your tax return and pay the taxes owed as soon as possible since the failure to pay and interest on the unpaid taxes will continue to accrue until the taxes are paid.
You can never get an extension on the time to pay your taxes. You can go to the IRS website and request a payment plan, which will reduce the late payment penalty but not eliminate it. However, payment plans require a nonrefundable application fee, so if you can pay the taxes within three months or less, it is usually cheaper to just pay the tax as soon as you can instead of applying for a payment plan. Including interest, the penalty for late payment is about 1% per month.
The penalty for filing late is much higher. You should file your tax return as soon as you can even if you can’t pay right away.