You can save the plate in the refrigerator or choose not to offer anything after the meal. The child will eventually eat a cold dinner or by the next meal, the child will be hungry. Temporary hunger will not hurt children, but it will teach them to take what is offered when it is offered. We can't make children eat, but we can make them wish they had. We can control snacks and between meal treats.
Sleep is even more obvious.
If we provide the right environment, sleep MAY come quickly. Provide quiet time before bed. Provide attention before leaving the child alone. Provide quiet activities such as reading or playing with soft toys before falling alseep. These are all helpful.