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

.grid {
  display: grid;
  grid-auto-rows: 100px;
  grid-template-columns:repeat(3,1fr);
  grid-gap: 5px;
}
.grid :nth-child(4n + 1),
.grid :nth-child(4n + 4){
  grid-column: span 2;
}

/**/
.grid {
  max-width:600px;
  margin:auto;
  counter-reset:num;
}
.grid *{
  border:2px solid;
  font-size:30px;
  box-sizing:border-box;
  font-family:sans-serif;
  display:grid;
  place-content:center;
}
.grid *:before {
  content:counter(num);
  counter-increment:num;
}