I don't believe it's necessary, but I'm not in the majority where I live. I tell my child what I want them to do, practice with them, and offer up a lot of positive reinforcement.

Keep the rules very simple and focus on the positive opposite. Tell them what you want them to do, not what you don't want them to do. Cognitively they cannot handle that. If you tell them to "stop running" they first have to imagine themselves running before they can imagine themselves not running. That's too much for them to process. Instead, you should tell them "walking." Easy rules: hands to yourself, stay by moms/dads side, feet on the floor, calm voice, etc... Pracrice with them and offer up praise and reinforcement. Sticker charts/point charts are good for this as well but they shouldn't take the place of you praising them.

Que them up if they need it, especially when you are first trying to build a new habit, and praise them anytime you get compliance. If you catch them doing it without you queuing them up, praise them.

One other thing to look at is extinction. Unless your child is a danger to themselves or others then do not intervene when they have a melt down. You can que them with: mommy/daddy/whatever can't understand you when you ______, so I'm going to need you to use your big girl/boy voice. When they comply, then engage with them. Most of the time they act up because they want a response from you and them melting down gets a response from you.

I always make sure I have an iPad or book with me so when we are out and about they have a distraction. I've also noticed when kids are tired and hungry they tend to act up so that's something to look at as well.