When you're in the filing flow, it'll ask how you want to pay. This is where you have the option to choose to "Pay later" if making monthly installments is a better option for you. Once your tax return has been accepted, head over to the IRS website directly to apply for a payment plan. It'll direct you to create or sign into your IRS Online Account.
Need more information on the process? You can go directly to this link to learn more https://www.irs.gov/payments/payment-plans-installment-agreements
Once you create an IRS Online Account, you'll be able to access your personal information, including balances, payment plans, and tax records. You can also view the notices and letters the IRS has sent you, and more!