Why? Spending more time outdoors during the day allows bright light to reach the back of the eye (retina) which stimulates dopamine release that may reduce eye growth. As parents we want our kids to grow but NOT their eyes. When the eye grows, so does increase nearsightedness (myopia).
So get outside and play! Ride a bike, scooter, play ball, swing
In addition, when your child is outside they are viewing objects in the distance, not close like a gamepad or phone.
Reading is great but like most things, moderation is key. Take breaks after 20 minutes. Encourage and set an example of good posture when reading. Maintaining closer distance less than 12 inches while reading and continuous readings > 30 minutes were risk factors of myopia development in children.