Markup: templates/output/06-components/social-media-icons/youtube.html
<div class="c-socialmedia-icon"><svg viewBox="0 0 36 36">
<path class="shape" fill="none" d="M1 1h34v34H1z"/>
<path class="icon icon--youtube" fill="currentcolor" d="M18 10s-6.254 0-7.814.418a2.503 2.503 0 0 0-1.768 1.768C8 13.746 8 18 8 18s0 4.254.418 5.814c.23.861.908 1.538 1.768 1.768C11.746 26 18 26 18 26s6.254 0 7.814-.418a2.505 2.505 0 0 0 1.768-1.768C28 22.254 28 18 28 18s0-4.254-.418-5.814a2.505 2.505 0 0 0-1.768-1.768C24.254 10 18 10 18 10Zm0 2c2.882 0 6.49.134 7.297.35a.508.508 0 0 1 .353.353c.241.898.35 3.639.35 5.297s-.109 4.398-.35 5.297a.508.508 0 0 1-.353.353c-.805.216-4.415.35-7.297.35-2.881 0-6.49-.134-7.297-.35a.508.508 0 0 1-.353-.353C10.109 22.399 10 19.658 10 18s.109-4.399.35-5.299a.505.505 0 0 1 .353-.351c.805-.216 4.415-.35 7.297-.35Zm-2 2.535v6.93L22 18Z"/>
</svg>
</div>
Source:
assets/sass/06-components/_components.socialmedia-icons.scss, line 47