<font-awesome-icon icon="fa-light fa-angle-left" />
<FontAwesomeIcon icon="fa-light fa-angle-left" />
.my-icon::before {
font: var(--fa-font-light);
content: "\f104";
}
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 512" style="width: 30px;height: 30px;fill: black">
<path d="M203.9 405.3c5.877 6.594 5.361 16.69-1.188 22.62c-6.562 5.906-16.69 5.375-22.59-1.188L36.1 266.7c-5.469-6.125-5.469-15.31 0-21.44l144-159.1c5.906-6.562 16.03-7.094 22.59-1.188c6.918 6.271 6.783 16.39 1.188 22.62L69.53 256L203.9 405.3z"/>
</svg>
<i class="fa-light fa-angle-left"></i>