Boilerplate:

<style>
  body {
    margin: 0;
  }
</style>

<script
  async
  src="https://unpkg.com/es-module-shims@1.6.3/dist/es-module-shims.js"
></script>

<script type="importmap">
  {
    "imports": {
      "three": "https://unpkg.com/three@0.150.1/build/three.module.js",
      "three/addons/": "https://unpkg.com/three@0.150.1/examples/jsm/"
    }
  }
</script>

<script type="module">
  import * as THREE from 'three'
  import { OrbitControls } from 'three/addons/controls/OrbitControls.js'

  const scene = new THREE.Scene()
  const camera = new THREE.PerspectiveCamera(
    75,
    window.innerWidth / window.innerHeight,
    0.1,
    1000
  )

  const renderer = new THREE.WebGLRenderer()
  renderer.setSize(window.innerWidth, window.innerHeight)
  document.body.appendChild(renderer.domElement)

  const controls = new OrbitControls(camera, renderer.domElement)

  const geometry = new THREE.BoxGeometry(1, 1, 1)
  const material = new THREE.MeshBasicMaterial({ color: 0x00ff00 })
  const cube = new THREE.Mesh(geometry, material)
  scene.add(cube)

  camera.position.z = 5

  function animate() {
    requestAnimationFrame(animate)
    renderer.render(scene, camera)
    cube.rotation.x += 0.01
    cube.rotation.y += 0.01
  }
  animate()
</script>