<font-awesome-icon icon="fa-thin fa-alt" />
<FontAwesomeIcon icon="fa-thin fa-alt" />
.my-icon::before {
font: var(--fa-font-thin);
content: "\e08a";
}
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 640 512" style="width: 30px;height: 30px;fill: black">
<path d="M416 440c0 4.418 3.582 8 8 8h208c4.418 0 8-3.582 8-8s-3.582-8-8-8h-208C419.6 432 416 435.6 416 440zM640 72C640 67.59 636.4 64 632 64h-136.8c-22.31 0-42.97 10.06-56.72 27.62L188.9 410.5C178.2 424.2 162.2 432 144.8 432H8C3.594 432 0 435.6 0 440S3.594 448 8 448h136.8c22.31 0 42.97-10.06 56.72-27.62l249.6-318.9C461.8 87.84 477.8 80 495.2 80H632C636.4 80 640 76.41 640 72z"/>
</svg>
<i class="fa-thin fa-alt"></i>