fa-sort-amount-up-alt icon in font awesome icons has 1 variant fas i.e.,solid.
fa-sort-numeric-down icon in font awesome icons has 1 variant fas i.e.,solid.
fa-sort-numeric-down-alt icon in font awesome icons has 1 variant fas i.e.,solid.
fa-sort-numeric-up icon in font awesome icons has 1 variant fas i.e.,solid.
fa-sort-numeric-up-alt icon in font awesome icons has 1 variant fas i.e.,solid.
fa-space-shuttle icon in font awesome icons has 1 variant fas i.e.,solid.
fa-square-root-alt icon in font awesome icons has 1 variant fas i.e.,solid.
fa-star-half-alt icon in font awesome icons has 1 variant fas i.e.,solid.
fa-steam-square icon in font awesome icons is part of brand (fab) icons
fa-step-backward icon in font awesome icons has 1 variant fas i.e.,solid.