<div class="grid">
  <div class="cell">lorem</div>
  <div class="cell">lorem</div>
  <div class="cell">lorem</div>
  <div class="cell">lorem</div>
  <div class="cell">lorem</div>
  <div class="cell">lorem</div>
</div>

body {
  background: #f3f3f3;
  padding: 20px;
  height: 100vh;
  box-sizing: border-box;
}
.grid {
  height: 100%;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  grid-gap: 20px;
}

.cell {
  background: #fff;
  border: 1px solid #ddd;
  border-radius: 5px;
  font-size: 20px;
  padding: 20px;
  
  &:nth-child(6n + 3) { grid-row: span 2; }
  &:nth-child(6n + 4) { grid-row: span 2; }
  &:nth-child(6n + 6) { grid-column: span 2; }
}