After you file

DawnC is correct. Wait to see if your return is rejected. 

If your return is rejected because you used your 2021 W-2 versus your 2022 W-2, the IRS wouldn't even see your first payment plan. When you correct your return, you'll be able to enter the payment plan again and you can add a payment.

If your return gets accepted, yes, you'll have to file an amended return. If your payment plan is the same with your amended return, you could pay the initial payment at any time. See Payments | Internal Revenue Service.

The IRS wouldn't reject your return for a payment plan. 

Per IRS What happens when I request a payment plan?

• When you request a payment plan (installment agreement), with certain exceptions, the IRS is generally prohibited from levying and the IRS’s time to collect is suspended or prolonged while an Installment Agreement (IA) is pending. 
• An IA request is often pending until it can be reviewed, and an IA is established, or the request is withdrawn or rejected. 
• If the requested IA is rejected, the running of the collection period is suspended for 30 days. Similarly, 
• if you default on your IA payments and the IRS proposes to terminate the IA, the running of the collection period is suspended for 30 days. 
• Last, if you exercise your right to appeal either an IA rejection or termination, the running of collection period is suspended by the time the appeal is pending to the date the appealed decision becomes final. 
• Refer to Tax Topic No. 160 - Statute Expiration Date and Tax Topic No. 202 – Tax Payment Options.