I have already filed for 2020 and discovered that I did make $650 in donations to charity. Does anyone know if we can claim the $300 credit in 21 for 20's tax return?

The cares act provides a $300 credit if you do not itemize.  This year, the standard deduction was more than my itemizations so I looked for donations but forgot those I made through my paycheck.  I've already filed.  I know I can amend but not sure if the additional refund would be worth it.  Looking to see if we can carry over this credit to 2021?