No, the payments that were setup to be made on 4/15 will not automatically change to the 7/15 deadline. Depending on the method the payments were setup to be made by, there are different options for canceling the payments and then rescheduling them for 7/15. 

From the IRS FAQs regarding COVID19 Reaction - Filing and Payment Deadlines Questions and Answers:

14. I already filed my 2019 income tax return that would have been due on April 15 and scheduled a payment of taxes for April 15, 2020. Will this payment be automatically rescheduled to July 15, 2020?

• If you scheduled a payment through IRS Direct Pay, you can use your confirmation number from the payment to access the Look Up a Payment feature. You can modify or cancel a scheduled payment until two business days before the payment date. The email notification you received when you scheduled the payment will contain the confirmation number.
• If you scheduled a payment through Electronic Federal Tax Payment System (EFTPS), click on Payments from the EFTPS home page, login, then click Cancel a Tax Payment from the left menu and follow the instructions. You must do so at least two business days before the scheduled payment date.
• If you scheduled a payment as part of filing your tax return (authorizing an electronic funds withdrawal), you may revoke (cancel) your payment by contacting the U.S. Treasury Financial Agent at 888-353-4537. You must call to make a payment cancellation request no later than 11:59 p.m. ET two business days prior to the scheduled payment date.
• If you scheduled a payment by credit card or debit card, contact the card processor to cancel the card payment.