You can file an extension thru TT now ONLY if you are military ... https://turbotax.intuit.com/irs-tax-extensions/
If not then you will need to mail in the form. https://www.irs.gov/pub/irs-pdf/f4868.pdf
Line 8—Out of the Country. If you are out of the country on the regular due date of your return, check the box on line 8.