gsap.registerPlugin({
  name: 'myCustomProperty',
  init(target, value) {
    gsap.to(target, {
      x: value.x,
      backgroundColor: value.backgroundColor,
      rotate: value.rotate,
      duration: value.duration
    })
  }
})

gsap.to('.box', {
  myCustomProperty: {
    x: 100,
    backgroundColor: 'red',
    rotate: 360,
    duration: 3
  }
})