You cannot and do not enter a dependent child's earned income reported on a W-2 on your tax return.
If the income on the W-2 is above the minimum filing requirement of $14,600 then the child will have their own tax return.
If the income is under the minimum filing requirement but there were taxes withheld from the wages, the child can file a tax return to get a refund of the taxes withheld. If they do file a return make sure that they indicate on their return that they can be claimed as a dependent.
