My child doesn't notice when others don't want it and gets too close or touches them.

Reading distance and others' signals is a skill learned gradually. Make it concrete and visible, such as "stay about one arm's length away" and "ask 'is this okay?' before touching." Explain on the spot that the other person pulling away, having a stiff expression, or saying "stop" are stop signals. When it doesn't go well, prevention works better than scolding—give a heads-up about distance beforehand, or have an adult step in. Practicing so your child can also say "stop" alongside this helps them learn equal relationships.