The CTC is limited to your tax liability. The additional child tax credit is calculated by taking subtracting $2,500 from your income and then multiplying that number by 15%. If you do not have more than $2,500 of eligible income, you would not qualify for the Additional Child Tax Credit. So if your total income was $3,350 then you would have an additional child tax credit of $127.50
The total per child is $2000. First the $2000 is used to reduce your tax owed down to zero. When (if) your tax owed is zero, the "rest" of the $2000 can be added to your refund as the Additional Child Tax Credit----up to a maximum of $1600 per child. But....that Additional Child Tax Credit also depends on how much you earned by working.
Take the amount you earned, subtract $2500, and multiply what is left by 15%. That is your additional child tax credit ---- up to a maximum of $1600 per child.
Look at your 2023 Form 1040 to see the child-related credits you received
PREVIEW 1040
https://ttlc.intuit.com/questions/1901539-how-do-i-preview-my-turbotax-online-return-before-filing
Child Tax Credit line 19
Credit for Other Dependents line 19
Earned Income Credit line 27
Additional Child Tax Credit line 28