<div class="container">
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
</div>

.container {
  display: inline-flex;
  align-items: center;
}

.item {
  width: 100px;
  height: 100px;
  background: orange;
  transition: all .5s;
}

.container:hover > .item:not(:hover) {
  height: 80px;
  background: black;
}