We have the [`fallback_intermediate_image_sizes`][1] filter within `wp_generate_attachment_metadata()`: ** * Filters the image sizes generated for non-image mime types. * * @since 4.7.0 * * @param string[] $fallback_sizes An array of image size names. * @param array $metadata Current attachment metadata. */ $fallback_sizes = apply_filters( 'fallback_intermediate_image_sizes', $fallback_sizes, $metadata ); where the default sizes are: $fallback_sizes = array( 'thumbnail', 'medium', 'large', ); [1]: https://github.com/WordPress/wordpress-develop/blob/4ad3cad2e0d9369d96f04837babe6270a1423487/src/wp-admin/includes/image.php#L594-L594