At least when your kids are toddlers, the goal is not primarily to control the children in restaurants, but mostly to control the damage.
In short, it is unrealistic to expect that your kid will not do bad things while waiting for food. They have the attention span of a gnat and the intelligence of a human. You have to choose which bad things are acceptable.
Not acceptable: Allowing them to run around the restaurant, chasing each other throughout the meal. This must be stopped.
Acceptable: Allowing your child to sing a little. This is even true if your child is singing “I got a poopy and a poopy and a poopy and a poopy! Poopy, poopy, poopy all the waaaay!”
At least it’s okay if it doesn’t carry very far out of your booth.
Anyway, it’s better than screaming.