We call functions like resize and modulate with their parameters in an object, which results in calls like:

sharp(input)
  .modulate({
    brightness: 0.5,
    saturation: 0.5,
    hue: 90
  });

sharp(input)
  .resize({ width: 100, height: 300 });

But this does not work:

sharp(input).sharpen({ sigma: 2, flat: 2, jagged: 3 }

What are you trying to achieve?
Symmetry with how I call other functions

Have you searched for similar feature requests?
Yes. My search did not turn up any issues.