If you qualify to get the additional child tax credit it is added to your refund automatically. That refundable credit is based on how much you earned by working. If you qualify for it, you get 15% of the amount above $2500 that you earned from working.
For your 2020 tax return there is a "lookback" in the earned income part of the software. You can choose whether to use your 2019 AGI or 2020 AGI to calculate the amount of earned income credit and child tax credit you get in your 2020 tax refund.
Look at your 2020 Form 1040 to see the child-related credits you received
PREVIEW 1040
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Child Tax Credit line 19
Credit for Other Dependents line 19
Earned Income Credit line 27
Additional Child Tax Credit line 28
Child and Dependent Care Credit line 31 (from line 13 of Schedule 3)