See this TurboTax support FAQ for filing an extension - https://ttlc.intuit.com/turbotax-support/en-us/help-article/internal-revenue-service/file-irs-extens...
Using the TurboTax desktop editions you can complete the extension request, Form 4868, then print and mail the extension request to the IRS.
Click on Federal Taxes
Click on Other Tax Situations
Under Other Tax Forms
On File an extension, click on the start button