When reading expand chapter, there is:
expand is useful when composing lambda expressions or doing variable expansion inside macros.
But the example code below is nothing to do with macros.
(expand (fn (base) (pow base power)) 'power))
(define square (raise-to 2))
(define cube (raise-to 3))
(square 5) → 25
(cube 5) → 125
perhaps better: "expand is useful when composing lambda expressions and doing variable expansion as in rewrite macros."