RemixIconEx.Media.fullscreen

You're seeing just the function fullscreen, go back to RemixIconEx.Media module for more information.
Link to this function

fullscreen(icon_css_class \\ "icon")

iex> Elixir.RemixIconEx.Media.fullscreen()
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" class="icon">
  <path d="M20 3h2v6h-2V5h-4V3h4zM4 3h4v2H4v4H2V3h2zm16 16v-4h2v6h-6v-2h4zM4 19h4v2H2v-6h2v4z" />
</svg>

example usage

svg.icon {
  width: 96;
  height: 96;
}