[Aetae]

<style>
html, body {
  width: 100%;
  height: 100%;
  padding: 0;
  margin: 0;

  overflow: hidden;

  display: flex;
  align-items: center;
  justify-content: center;
}
.img {
  cursor: pointer;
  transition: transform 3s;
}
.scale {
  transform: scale(3);
}
</style>
<img class="img" src="https://javascript.ru/forum/images/ca_serenity/misc/logo.gif" onclick="classList.toggle('scale')">