You can file an extension request for a 6 month extension to file your tax return up through October 15, 2019. However, if you have taxes owed those taxes have to be paid on or before April 15, 2019 to avoid a failure to file penalty.
If you have no taxes owed or are receiving a tax refund there are not penalties for filing after the due date of the tax return.
Go to this TurboTax website to e-file an extension request - https://turbotax.intuit.com/irs-tax-extensions/