In the article An Unexpected Key to Healthier Child Development: And constructive ways to encourage it., Claudia Skowkron says "Allowing space for ‘boredom’ encourages creative thinking and problem-solving skills. Instead of following a schedule and going to the next task, the child will need to make a decision on how to occupy their time."
If I ever told my parents I was bored as a child, they always told me to go find something to do. And that is what I did. That is what many of us did. When we constantly fill children's time with screens or adult-led activities, we rob them of the opportunity to figure out how to handle boredom and be creative and find something to do.
So, instead of worrying about finding something for children to do, let them get bored and figure it out!