if you already filed 2020, don't bother. based on what you provided that only the social security tax withheld increased on the w-2 there is no reason for you to file an amended return or even change the numbers in Turbotax.
if you are filing your 2020 1040 for the first time in the w-2 section for box 4 enter 6000. you'll come to some questions check the one that says w-2 was corrected by my employer.
