You cannot include your child's earned income on your tax return.
If he has $2,500 of income on a W-2 he is not required to file a tax return. He might want to file to get a refund of income tax that was withheld. Social Security and Medicare taxes cannot be refunded. If no federal or state income tax was withheld, there is nothing to be refunded.
If he has $2,500 of income that is not on a W-2 he is required to file a tax return. It doesn't matter whether he got a 1099-NEC, a 1099-MISC, or no tax form. He will not have to pay any income tax, but he will have to pay self-employment tax.
If he files a tax return for any reason, make sure he checks the box that says someone can claim him as a dependent.
