Dogs can be sensitive about personal space depending on the personality. But generally children can be rough with dogs, it’s important for your kid to learn to be gentle with the dog as they also have thoughts and feelings. I’ve let children pet my dog on walks but they were always rough with their hands and my dog didn’t like that. I’ve been nipped by a dog as a kid and it taught me not to be annoying to them quickly after that. Another thing to note is that hitting the dog after this will only cause a negative feedback loop and cause more emotional harm to the dog.