<div class="grid">
  <div style="--aspect-ratio: 2/1;">2/1</div>
  <div style="--aspect-ratio: 3/1;">3/1</div>
  <div style="--aspect-ratio: 1/1;">1/1</div>
</div>

.grid {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  place-items: start;
}
.grid > * {
  background: orange;
  width: 100%;
}
.grid > [style^='--aspect-ratio']::before {
  content: "";
  display: inline-block;
  width: 1px;
  height: 0;
  padding-bottom: calc(100% / (var(--aspect-ratio)));
}