You can efile a 2021 amended return. See step 10 for Online versions.
https://ttlc.intuit.com/community/tax-return/help/how-do-i-amend-my-2021-return/00/2544441
But I seem to recall there are certain situations that you can't efile like changing the status. Or how did file the original return? Was it efiled and accepted?
