Here is a link with more information on how to file an extension through TurboTax.
https://turbotax.intuit.com/irs-tax-extensions/
If you are referring to the automatic two month extension, here is a link with more information regarding that:
https://www.irs.gov/individuals/international-taxpayers/u-s-citizens-and-resident-aliens-abroad-auto...This is an excerpt from the above link:
You may be allowed an automatic 2-month extension of time to file
your return and pay any federal income tax that is due. You will be
allowed the extension if you are a U.S. citizen or resident alien and on the regular due date of your return:
- You are living outside of the United States and
Puerto Rico and your main place of business or post of duty is outside
the United States and Puerto Rico, or
- You are in military or naval service on duty outside the United States and Puerto Rico
