align-self その子だけ交差軸の寄せを変える

<div class="row">
  <span>中央</span>
  <span class="end">下だけ</span>
</div>

.row {
  display: flex;
  align-items: center;
  min-height: 5rem;
  gap: 0.4rem;
  background: #f3f1ec;
  padding: 0.4rem;
}
.row > span {
  background: #efeef8;
  padding: 0.3rem 0.6rem;
}
.end {
  align-self: flex-end;
}