JSFiddle - React, Tailwind, and code Playground

HTML

<p class="growsandstays">This grows and stays big.</p>

CSS

@keyframes grow {
  0% { font-size: 0; }
  100% { font-size: 40px; }
}

.growsandstays {
  animation-name: grow;
  animation-duration: 3s;
  animation-fill-mode: forwards;
}