<font-awesome-icon icon="fa-thin fa-angle-down" />
<FontAwesomeIcon icon="fa-thin fa-angle-down" />
.my-icon::before {
font: var(--fa-font-thin);
content: "\f107";
}
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 384 512" style="width: 30px;height: 30px;fill: black">
<path d="M191.1 352c-1.1 0-3.969-.7344-5.531-2.219L34.47 205.8c-3.187-3.047-3.312-8.125-.25-11.31c3.094-3.188 8.156-3.281 11.31-.25l146.5 138.7l146.5-138.7c3.219-3.031 8.281-2.938 11.31 .25c3.062 3.188 2.937 8.266-.25 11.31l-151.1 144C195.1 351.3 193.1 352 191.1 352z"/>
</svg>
<i class="fa-thin fa-angle-down"></i>