Preface by saying I am not an expert!! But I have been reading up on this and working on a dummy myself. It does have some wordless pages. Formatting this into dummy script was the most annoying part because it's the least "fun" but it's better than having to mock up an entire book. There are a few ways to do this apparently so it's malleable, this is how I did mine:
Page 1/ Chapter 1
A sundog, newly rolls off of a cloud, tumbling head over heels through the sky
A sun puppy, with reflections of gold and rainbow, he plays in the sky, becoming more puppy-like and less cloudy.
King Finvarra smiles at the sky. He holds a bound book and walks to sit under the tree of knowledge.
The tree is large and the sunlight under it is dappled and sparkling. He seems patient, old, and wise with intricate faerie wings and a crown inspired by spring branches.
Finvarra settles in under the tree and opens the book. The book is blank. An inkwell and quill appear in mid-air next to the book and King Finvarra dips the quill and writes “Once upon a time...”
I should maybe be going in to even more detail per panel but I am honestly hoping to get more feedback about it once I start querying it. I have 50 pages done per panel and page like this with the rest of the book in a synopsis.