No, the Child Tax Credit and Additional Child Tax Credit for 2020 remain at under 17 years old. But, you are correct for 2021. The rules do change to provide $3,600 for each child under 6 and $3,000 for children 6-17 from $2,000 for children under 17.
To see the 2020 rules for Qualifying Child for the Child Tax Credit, click 2020 Publication 972 Child Tax Credit and Credit for Other Dependents.
For more information, see: How will the third stimulus impact me?
