<font-awesome-icon icon="fa-thin fa-angle-left" />
<FontAwesomeIcon icon="fa-thin fa-angle-left" />
.my-icon::before {
font: var(--fa-font-thin);
content: "\f104";
}
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 512" style="width: 30px;height: 30px;fill: black">
<path d="M32 255.1c0-1.1 .7344-3.969 2.219-5.531l144-151.1c3.047-3.187 8.125-3.312 11.31-.25c3.188 3.094 3.281 8.156 .25 11.31L51.08 255.1l138.7 146.5c3.031 3.219 2.938 8.281-.25 11.31c-3.188 3.062-8.266 2.937-11.31-.25L34.22 261.5C32.73 259.1 32 257.1 32 255.1z"/>
</svg>
<i class="fa-thin fa-angle-left"></i>