WordPress Plugin: Remove Unwanted Image Sizes

cdm-remove-unwanted-image-sizes.php

<?php
/**
 * Plugin Name: Remove Unwanted Default Image Sizes 
 * Plugin URI: https://gist.github.com/chrisdavidmiles/6fd21201d16f8a7e434b06b903d4706c
 * Description: This removes three default image sizes that I don't want: medium_large, 1536x1536, and 2048x2048.
 * Author: Jochen Gererstorfer
 * Author URI: https://bloggerpilot.com/en/disable-wordpress-image-sizes/
 * Version: 0.3
 */

if ( ! defined( 'ABSPATH' ) )  die; 

// Remove medium_large
add_filter('intermediate_image_sizes', function($sizes) {
  return array_diff($sizes, ['medium_large']);  // Medium Large (768 x 0)
});

// Remove 1536x1536 and 2048x2048
add_action( 'init', 'cdm_remove_large_image_sizes' );
function cdm_remove_large_image_sizes() {
  remove_image_size( '1536x1536' );             // 2 x Medium Large (1536 x 1536)
  remove_image_size( '2048x2048' );             // 2 x Large (2048 x 2048)
}

// disable WordPress 5.3 image downscaling feature
add_filter( 'big_image_size_threshold', '__return_false' );