Yes. You are allowed to use last year's income (2019) instead of this year's income (2020) to calculate the Child Tax Credit.
Earning more income in 2019 would mean the Child Tax Credit could potentially be larger depending on the rest of your circumstances.
TurboTax will walk you through this election in the Deductions & Credits section where you read the message that this was an option.
If you would rather calculate this yourself, click the link to use the worksheet on page 10 of Publication 972 Child Tax Credit and Credit for Other Dependents.
