SOURCE

<div class="outer">
  <img class="inner" src="https://www.isanxia.com/zb_users/upload/2020/10/202010301604026617513960.jpg" />
</div>

.outer {
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid #aaa;
  resize: both;
}

.inner {
  background-color: green;
  aspect-ratio: 4 / 3;
  max-height: 100%;
  max-width: 100%;
}