How to increase radius of a cylinder using buffer geometry?

I am trying to increase the length and radius and length of a cylindrical gltf model. I was able to increase the length by

function updateModel (len) {
    for (let i = 0; i < model.children[0].geometry.attributes.position.count; i++) {      
      let z = model.children[0].geometry.attributes.position.getZ(i);
      let sgnZ = Math.sign(z);
      model.children[0].geometry.attributes.position.setZ(i,  z + len * sgnZ);
    model.children[0].geometry.attributes.position.needsUpdate = true;

But it didn’t work very well with the x and y axes the model got deformed. is it possible to increase the radius/diameter using the geometry of a mesh?
This is the model I tried to edit :
shaft.gltf (21.0 KB)