JSFiddle - React, Tailwind, and code Playground

HTML

<button onclick="iniciar()">Picture in Picture</button>

<video src="https://static.pexels.com/lib/videos/free-videos.mp4" id="meu-video" controls></video>

CSS

video{
  width: 100%;
  margin: 18px auto;
}

JavaScript

var mybutton = document.querySelector('button');

mybutton.addEventListener('click', iniciar);

async function iniciar() {
  const video = document.querySelector('#meu-video');
  await video.requestPictureInPicture();
}