hoppscotch/packages/hoppscotch-app/assets/icons/maximize-2.svg

<svg
  xmlns="http://www.w3.org/2000/svg"
  width="24"
  height="24"
  viewBox="0 0 24 24"
  fill="none"
  stroke="currentColor"
  stroke-width="2"
  stroke-linecap="round"
  stroke-linejoin="round"
>
  <polyline points="15 3 21 3 21 9" />
  <polyline points="9 21 3 21 3 15" />
  <line x1="21" y1="3" x2="14" y2="10" />
  <line x1="3" y1="21" x2="10" y2="14" />
</svg>