To clarify the prior answers, 2021 (which is past the date to get a refund, unless you filed an extension for the 2021 return) was the only year to get the REFUNDABLE Child Tax Credit without 'earned' income.
For the other years, if you had other income that resulted in income tax, you can still claim the Child Tax Credit to offset that income tax. But without any 'earned income (such as a W-2 or self-employment income) only any withholding you had would be refunded to you; you can't get any Child Tax Credit "refunded" to you except for 2021.
