If you applied for the ITIN renewal after the due date of the 2020 tax return, May 17, 2021, you are not eligible for the 2020 child tax credit.
IRS Publication 972 Child Tax Credit and Credit for Other Dependents - https://www.irs.gov/pub/irs-pdf/p972.pdf
You must have a TIN by the due date of your return.
If you, or your spouse if filing jointly, do not have an SSN or ITIN issued on or before the due date of your 2020 return (including extensions), you cannot claim the CTC, ODC, or ACTC on either your original or an amended 2020 return.
If you apply for an ITIN on or before the due date of your 2020 return (including extensions) and the IRS issues you an ITIN as a result of the application, the IRS will consider your ITIN as issued on or before the due date of your return.
