$fid = $variables['elements']['field_image_media'][0]['#item']->entity->id();
$file = File::load($fid);
// Get origin image URI.
$image_uri = $file->getFileUri();
// Load image style "thumbnail".
$style = ImageStyle::load('uncropped');
// Get URI.
$uri = $style->buildUri($image_uri);
// Get URL.
$url = $style->buildUrl($image_uri);
$image_factory = \Drupal::service('image.factory')->get($image_uri);
$height = $image_factory->getToolkit()->getHeight();
$width = $image_factory->getToolkit()->getWidth();
$variables['field_image_media_extra'] = [
'url' => $url,
'height' => $height,
'width' => $width,
];