If you want to pay your 2021 estimated taxes, you will have to make the payments yourself. You can pay online at www.irs.gov/payments. You can make more than one payment per quarter, in fact, you can make tax payments to your account as often as you like. As far as I know however, you can’t set up automatic payments, you would have to remember to login and make your payments whenever you prefer, such as once a month.
If you have a business and make your tax payments through EFTPS, you will have to log in there and see if they have an automated payment feature. I think they don’t, because it would be logical that business tax payments would vary depending on the hours worked by their employees, but I haven’t used EFTPS in many years.
If you owe taxes for a 2020 or earlier tax return and can’t afford to pay them in a lump sum, there is a procedure to request a payment plan from the IRS. When requesting a payment plan for past due taxes, there is a nonrefundable start up fee, and that start up fee will be lower if you agree to have your payments automatically deducted from your bank account on a monthly basis. The start up fee is higher if you want to pay by check.
