No. And you do not get stimulus money for him since he is over 16. He can still be claimed as a dependent --dependents cannot receive stimulus money.
well.... there really isn't enough detail to understand whether this 18 year old is a dependent or indepedent.
Does he live at home? is he still in school? do you provide more than 50% of his support? then yes, he is your dependent and not eligible for the stimulus.
However, if he is living on his own, earning money, etc. then different story.
please read this article... if you CAN claim him as your dependent (whether you do or not is immaterial) , he is not eligible for the stimulus.