Create a class to hold your grid with display set to grid:
<style>
.grid {
display: grid;
grid-template-columns: repeat(3, 50px);
}
</style>
Now apply this class to a div and add elements inside it like you normally do:
<div class="grid">
<p>Paragraph</p>
<div>Div</div>
<h3>Heading 3</h3>
</div>
Above code will get displayed something like this:

Note that once you add more than 3 nested elements into your grid
div, you will find them getting arranged row by row in threes.
For example, consider the code block below:
<div class="grid">
<p>1</p>
<p>2</p>
<p>3</p>
<p>4</p>
<p>5</p>
<p>6</p>
<p>7</p>
<p>8</p>
<p>9</p>
<p>10</p>
<p>11</p>
</div>
will produce this output:
