Extension:RelatedImages shows several "related images" on pages like [[File:Something.png]].
These recommended images are randomly chosen from the same categories as Something.png.
Everything is optional:
$wgRelatedImagesMaxCategories = 1; // Default: 3
$wgRelatedImagesMaxImagesPerCategory = 4; // Default: 3
$wgRelatedImagesIgnoredCategories = [ 'Some_category', 'Another_category' ]; // Default: []
$wgRelatedImagesThumbnailWidth = 120; // Default: 50
$wgRelatedImagesThumbnailHeight = 100; // Default: 50
// If the wiki uses [https://commons.wikimedia.org/wiki/Help:Image-Annotator],
// this should disable annotations on recommendation thumbnails.
$wgRelatedImagesBoxExtraCssClass = 'wpImageAnnotatorControl wpImageAnnotatorOff';
// Default values:
$wgRelatedImagesDisableForExtensions = [ 'ogg', 'pdf' ];
$wgRelatedImagesDoNotRecommendExtensions = [ 'ogg', 'pdf' ];