Question

How do the areas of the murals change when the width changes

Answer 1

 I do not completely understand your question, but if you mean area by "murals", then when the width increases, area does, too. For example:
I have a rectangular board that is 5 feet by 3 feet. The area is 15 square feet. I have another board with a longer width, but the same length. It is 5 feet by 4 feet. Its area is 20 square feet.