how to I add my 18 years w-2 if he worked for year 2024 part time

He will file his own tax return.  You do not include his income on your return.

If he is single, in school and didn't earn over $13,850 (Standard Deduction) he does not have to file a tax return; however if he had Federal or State Income Tax  withheld, it may be worth his while.

• You can still claim him as a dependent.
• On his tax return he will indicate that he can be claimed by someone else.
• This is in the My Info, or Personal Information section of TurboTax. 

These are reasons that your son would be required to file a tax return.

• His income is over the filing requirement   Single Under 65 $13,850
• He has over $400 in net earnings from self-employment (side jobs or other independent work)
• He had other situations that require you to file
• It might pay you to file even if you don’t have to.