Uses: grid-row-start and grid-row-end to
span rows. Columns are similar. Had to use flex on item 6 to justify and align.
.grid-container {
display: inline-grid;
grid-template-columns: auto auto auto auto;
column-gap: 50px;
row-gap: 20px;
background-color: indianred;
padding: 10px;
}
.grid-item {
background-color: powderblue;
text-align: center;
padding: 20px;
font-size: 30px;
}
.item1 {
grid-column-start:1;
grid-column-end:3;
}
.item6 {
grid-row-start:2;
grid-column-start:3;
grid-row-end:span 2;
grid-column-end:span 2;
display:flex;
align-items: center;
justify-content: center;
}
<div class="grid-container">
<div class="grid-item item1">1</div>
<div class="grid-item">2</div>
<div class="grid-item">3</div>
<div class="grid-item">4</div>
<div class="grid-item">5</div>
<div class="grid-item item6">6</div>
<div class="grid-item">7</div>
<div class="grid-item">8</div>
</div>