JSFiddle - React, Tailwind, and code Playground

HTML

<div id="title">
Hello
</div>

CSS

#title {
  background: red;
  transform: scale(1);
  transition: transform 1s;
}

#title.smaller {
  transform: scale(0.3);
}

JavaScript

setTimeout(function() {
// Doesn't work
document.getElementById("title").classList.add("smaller");

// Doesn't work either
//document.getElementById("title").style.transform = 'scale(0.3)';
}, 1000);