You only have to pay more if you need to upgrade to a higher version to enter something.
Has your 2021 original return been Accepted? You need to wait for it to fully process and you get the first refund. Then you can Amend. So it might be a long wait.
How to Amend
https://ttlc.intuit.com/community/amending/help/how-to-amend-change-or-correct-a-return-you-already-...
