ad,
<code>layer_static_mapbox()</code> is based largely on <code>layer_mapbox()</code> in the snapbox package
(available under a <a href="https://github.com/anthonynorth/snapbox/blob/master/LICENSE" class="external-link">MIT license</a>. There
are a few key differences between <code>layer_static_mapbox()</code> and
<code>layer_mapbox()</code>. The "scale" parameter is equivalent to the
"scale_ratio" parameter for snapbox. Setting <code>scale_factor = "2x"</code> is
equivalent to setting <code>retina = TRUE.