Do kids outgrow thumb sucking?

One of my 5.5yo twins sucks his thumb (switched to thumb from paci when we took it away at 3yo) and I’m wondering if anyone has experience with kids just growing out of it with no intervention? I don’t like the nasty nail polish or giving him a punishment for it. We’ve given him other “chewies” but he always goes for the thumb still. He sucks his thumb in any moment where his hands aren’t active, pretty much - so when he’s watching TV, listening to reading, waiting for his food, etc. He definitely has his thumb in his mouth way more than he ever had the paci. He also doesn’t seem embarrassed by it yet but maybe peer pressure will stop it as he gets older?