.item h2
{
  text-decoration:underline;
  text-decoration-thickness: 12px;
  text-decoration-color: yellow;
  text-decoration-skip-ink: none;
  text-underline-offset:-7px;
}

<div class="section-grid">
    <div class="item"><h2>Some text that might<br>have a line break</h2></div>
</div>