How can i file new york state extension

If you already completed (or are mostly finished with) your 2018 state return in TurboTax Online, go back into your state and look for a Need more time to file? or similar extension question or option, usually towards the end of the interview (step through your state again from the beginning if you didn't find it). Then follow the onscreen instructions in TurboTax.

Otherwise, if you haven't (or you just) started your 2018 state return, scroll down to your state for alternative instructions.