You don't need a camp area for your child. Your own backyard will work. Take away the phone / the tablet / the laptop. Tell your child to invite friends over. Make snacks and have water available. If they had things like a jump rope / empty boxes to make forts out of / any kind of balls (basketballs, soccer balls, big bouncy balls), etc.
Then go back in the house and let them just play. Let them use their imagination and get dirty and just play. That's the best thing you can do for them. Provide a safe place for them to play and let the kids do their thing.