My very affectionate 18m old..what do I do?

Hey y'all!

So I have a wonderful 18m old boy. He is just the sweetest and most affectionate little guy. He loves waving and giving hugs. He comes from a household where my husband and I give each other hugs and kisses and of course, smother our baby. We do respect his boundaries though if he's uninterested. He does love his family hugs and pushing mom and dad's heads together to make them kiss lol

Anyway, he's recently started giving his teachers hugs and that has grown into other parents. Yesterday and today, he was aggressively giving other kids hugs (and some even trying to kiss them). It was cute...until it was clear the other one didn't like it. One of the little kids even said no. I pulled my boy when the kid was clearly uncomfortable and told him the other kid wasn't in the mood for a hug and we need to respect them (I know he doesn’t entirely know what that means).

Anyway, any tips on how to address boundaries this young? How do I address it age appropriately as he grows? I'm grateful it's hugging and not hitting or throwing things, but he still needs to learn sometimes people don't want hugs and we need to respect people's bodies and choices.