How to render an image at its original size?
You can also use the #theme property image (which does not appear to be documented anywhere), but gives a valid image tag.

$render= [
  '#theme' =&gt; 'image',
  '#uri' =&gt; $file-&gt;getFileUri(),
];


Which becomes &lt;img src="/sites/default/files/image.png" alt="" /&gt; once rendered.