CODE EXAMPLE FOR HTML

youtube embed autoplay not working

since April of 2018 because Google decided to give greater control
of playback to users.
You just need to add &mute=1 to your URL. 
<iframe
            className="w-[95%] h-[80%] box-shadow"
            src="https://www.youtube.com/embed/MkrNEj4RrbA?autoplay=1&mute=1"
            title="YouTube video player"
            frameborder="0"
            allow="accelerometer;fullScreen; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture;"
            allowFullScreen
  ></iframe>