system-uicons/src/images/icons/expand_width.svg

<svg height="21" viewBox="0 0 21 21" width="21" xmlns="http://www.w3.org/2000/svg"><g fill="none" fill-rule="evenodd" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round" transform="translate(1 2)"><path d="m.5.5v16.021"/><path d="m18.5.5v16.021"/><path d="m12.507 12.515 4-4-4-4.015"/><path d="m6.507 12.515-4-4 4-4.015"/><path d="m16.5 8.5h-14"/></g></svg>