This little one is literally getting their feet wet for the first time! Perhaps that is the best way for a child to experience their first time at the lake? Get their tiny feet wet. In that way they will feel more comfortable going in a little deeper each time.
Feet usually get so warm in shoes so when they initially hit that water it gives the youngster a most refreshing feeling. The child can wiggle their toes and push that refreshing water between them. Then they can slightly bury their feet in the sand beneath the water and pull them out ever so gently as the sand caresses their feet.
Then, in very shallow water, allow your child to take a seat in the water and observe everything that occurs from that point forward. My nephew began playing with his hands in the sand beneath the water and exploring everything in sight including trying to grab a few minnows. And that became his first fishing experience.
Make sure you document all this with photographs so that you can later share your child’s first experiences in the lake with them. What a splash that will make on their life!