<div style="height: 100vh;"></div>
<div class="box11" style="width: 90vw;height: 400px;border:2px solid red">
  <div class="box5" style="width: 50px;height:200px;border:2px solid red"></div>
</div>

gsap.registerPlugin(ScrollTrigger);
let t1 = gsap.timeline({
  scrollTrigger: {
    trigger: ".box11",
    start: "top bottom",
    scrub: true,
    markers: true
  }
});

t1.to(".box5", { x: 350 });