h2 {
    overflow: hidden;
}

h2:after {
    content:"";
    display: inline-block;
    height: 0.5em;
    vertical-align: bottom;
    width: 100%;
    margin-right: -100%;
    margin-left: 10px;
    border-top: 1px solid black;
}

<h2>Featured products</h2>

.parent {
    display: grid;
    grid-template-columns: auto 1fr;
    align-items: center;
}

 .line{
    background:black;
    height:1px
}

<div class="parent">
  <div>My some text</div>
  <div  class="line"></div>
</div>