He's big enough, it's just a matter of if they stress him out or not. They aren't worth the stress if they don't like it, but some of them settle in and relax in a
bath. It varies between dragons. The water should feel warm on the inside of your wrist, no more, and the water level should be up to about his armpits. Sometimes they like having a washcloth at the bottom to give them some traction. If he doesn't settle in then I would avoid baths unless he gets stinky or soiled and needs one. You can always offer supplemental water by dripping water on his nose for him to lick up.