In children’s self-defense classes, are they effective or is it more of a “my kid is so cute with their little fists up“ thing?

I don’t have kids myself, and I’m genuinely curious if Kids self-defense classes are effective, these would be classes for toddlers and young elementary aged kids. A lot of the kids look pretty vicious and tough, plus when kids have a tantrum to my knowledge, they can hold their own pretty well, especially when they throw themselves on the floor and refuse to go anywhere.

Can a five year old little girl in preschool, or a seven-year-old who is in elementary, physically defend themselves and take out a real world adult attacker? I know in a lot of the classes you see Children and toddlers who are black belts in a fighting/punch position and they look pretty tough. I mean, would the kid be able to punch/take out an adult? how would it look or what would the outcome be in the real world?