Step 1. Calculating the number of multiplications needed using N = log(Z/X, Y)

Step 2. Using scan to multiply X by Y for N times.

Like below: Formula in cell B7: =B1

Formula in cell B8:

=LET(x, B1, y, B2, z, B3, num_operations, ROUNDUP(LOG(z / x, y), 0), SCAN(x, SEQUENCE(num_operations), LAMBDA(current,dummy, current * y)))