Dependant son age 26 at home with w-2 $5,000 and withholding tax refund due, How to report on parent's return please?

[DoninGA]

If this is for a 2023 tax return, you cannot claim him as a dependent on your tax return since his gross income is $4,700 or more.  He would file his own tax return to get a tax refund of the federal taxes withheld from his wages on the W-2.

[Opus 17]

A child who has income from working must always report their income on their own tax return in their own name, even if they are also a dependent.

And in this case, because the child is over age 23 and has income more than $4700 (for 2023), you can't claim them as a dependent.