Shoulf I file for amendment, For stimulus check amount i added 2021 and 2020 instead of just putting 2020?

You were supposed to enter whether you received the 1st and/or 2nd stimulus checks----even though many people received the 2nd check in early 2021 you were supposed to answer that you received it -- if you got it--no matter whether you received in late 2020 or early 2021.

There are no questions about the3rd stimulus check on a 2020 return so there was no place to enter anything about the check for $1400.

If you have an amount on line 30 of your Form 1040 for the recovery rebate credit, then the IRS will cross check to see what you received.   If you made a mistake it will delay processing your return because it will require special handling.

Do NOT amend for it if you made a mistake.