Husband and wife should have each received a 6419 letter with half of the total ACTC issued.  If they did not file a joint return in 2021, each should have reported on their tax return only the amount from their respective 6419 letters.  So yes, it possible for the wife to receive additional child tax credit on her return.

IRS has lots of information available  https://www.irs.gov/credits-deductions/2021-child-tax-credit-and-advance-child-tax-credit-payments-f...