RemixIconEx.System.arrow_down

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

arrow_down(icon_css_class \\ "icon")

iex> Elixir.RemixIconEx.System.arrow_down()
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" class="icon">
  <path d="M13 16.172l5.364-5.364 1.414 1.414L12 20l-7.778-7.778 1.414-1.414L11 16.172V4h2v12.172z" />
</svg>

example usage

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