The increased child tax credit is for 2021, not 2020. It will not change your 2020 tax return or your refund. You will be able to get the increased credit on your 2021 tax return that you file next year.
You are supposed to be able to receive advance payments of part of the 2021 child tax credit starting in July. The IRS has not yet provided any details of how that is going to work.
