9 Things to Say to Your Anxious Child

1. I'm here with you. You are safe.

2. Do you want to do some dancing or running to get rid of the worried energy?

3. Tell me about it.

4. What would you like to say to your worry? What might your worry say back? Then what?

5. Let's draw it.

6. What does it feel like in your body? Where is the worry? How big is it?

7. Match your breaths to mine. 

8. Let's think up some endings for what could happen (anxious ones, goofy ones, and realistic ones)

9. What's something we could do to help you feel better?

more information from https://childmind.org/article/what-to-do-and-not-do-when-children-are-anxious/