unless you unenroll you will receive the credits based on your 2020 return. you may have to repay some of the excess credits when you file your 2021 return.
you can unenroll at this website
see this link for info on who may need to repay
As far as we know, the round 3 stimulus ($1400 per person) will not have to be paid back if your tax situation changes.
However, the $3000 or $3600 enhanced child tax credit will definitely have to be repaid if you receive advance payments but don't qualify on your 2021 tax return because you don't claim qualifying child dependents.