There is no deduction for dependents. Exemptions (deductible amount) was eliminated starting in 2018. Instead, you get a tax credit for each dependent, the child tax credit for children under 17 (under 18 for 2021 only) and the "Other Dependent Credit" for all others. The Other Dependent Credit is a maximum of $500 and is non refundable (you must have a tax liability to offset).
The child tax credit (CTC) is also limited to your tax liability. The CTC is a non-refundable credit and can only reduce your income tax to 0, It can not help you beyond eliminating your tax liability. But, if you have more than $2500 of earned income, some or all of it is usually given back to you thru the "Additional Child tax credit". That is, part of the CTC may be on line 28 of form 1040 (2021 & 2022) instead of line 19. The ACTC is calculated on form 8812 and is basically 15% of your earned income over $2500. The ACTC is a maximum of $1500 per child (not $2000).
