Recover Rebate Credit

That's a great question.  Let's review:

1)  If you pleased IRS by filing early and owed taxes for prior years, they took your RRC refund. 

2)  If you waited until now, IRS changed its mind thanks to some pressure from Congress and the NTA, and has announced it will not apply your RRC to prior-year taxes.

https://www.taxpayeradvocate.irs.gov/news/nta-blog-update-on-offset-of-recovery-rebate-credits-the-irs-has-agreed-to-exercise-its-discretion-to-stop-offsets-of-federal-tax-debts/

3)  But it's not clear to me whether taxes owed for 2020 will also be offset by the RRC.  Probably.  Even though IRS screwed up on sending many EIPs, especially the second one.  

This one: "or will the payments be applied to his balance owed?"

A credit is applied to taxes owed. A Refundable credit means it would even be paid out, if not used up against what you owe. For instance, if the person has a standard deduction that results in no income taxes computed, and also have Refundable Credits, they still get a payout, but not for any type of credit. Only the Refundable credits are payouts in that example.

It's on the Form 1040 for 2020:

Total tax Line 24

Recovery Rebate Line 30

Line 32: Add Lines 27 through 31 = your total other payments and refundable credits

Line 33: Add Lines 25d, 26 and 32 = these are your total payments

Line 34: If line 33 is more than line 24...overpaid

or;

Line 37: Subtract line 33 from line 24. This is the amount you owe now.