You have until October 15 to e-file. After that, your return will have to be filed by mail. If you are getting a refund, you have three years to file and receive the refund. If you owe tax due, you were supposed to pay the estimated tax by April 15, 2025. Did you do that?
You are indicating you did file an extension so you have until October 15, 2025 to file your return. This extension of time to file is not an extension to pay taxes due. File your return and pay any taxes due immediately to stop new penalties and interest from being accrued.
If you are assessed penalties there are remedies.
When the IRS waives a penalty it is called abatement. If you are unable to get the penalties waived and cannot afford to pay in full it may benefit you to enter into an installment agreement to make manageable monthly payments. Here is a link with further information including the latest on The One Big Beautiful Bill: IRS penalty abatement