<ul class="list animate">
  <li class="item item1"></li>
  <li class="item item2"></li>
  <li class="item item3"></li>
</ul>

body {
  background-color: magenta;
  display: flex;
  justify-content: center;
  height: 100vh;
  align-items: center;
}

.list {
  width: 500px;
  height: 200px;
  padding: 20px 30px;
  box-sizing: border-box;
  background-color: white;
  transition-duration: .5s;
  list-style-type: none;
}

.item {
  background-color: darkmagenta;
  height: 40px;
  margin-top: 10px;
}

.list:not(.animate) .item {
  transition-duration: .5s;
  transition-property: transform, visibility;
  transform: translateX(-20%);
  visibility: hidden;
  opacity: 0;
}

.list.animate .item1 {
  animation: list-show .2s 1;
}
.list.animate .item2 {
  animation: list-show .4s 1;
}
.list.animate .item3 {
  animation: list-show .6s 1;
}

@keyframes list-show {
    from {
        visibility: hidden;
        opacity: 0;
        transform: translateX(20%);
    }
    to {
        visibility: visible;
        opacity: 1;
        transform: translateX(0);
    }
}