<div class="wrapper">
  <div class="block">
    <div class="wrap"></div>
  </div>
</div>

.wrapper {
  background-color: black;
}
.block {
  max-width: 300px;
  aspect-ratio: 1 / 1;
  background-color: yellow;
}
.wrap {
  max-width: 200px;
  aspect-ratio: 16 / 9;
  background-color: red;
}