<?php 
/**
 * Plugin Name: Enable Major Core Updates
 */
add_filter( 'allow_major_auto_core_updates', '__return_true' );
add_filter( 'auto_update_plugin', '__return_false' ); 
remove_action( 'load-update-core.php', 'wp_update_plugins' );
add_filter( 'pre_site_transient_update_plugins', create_function( '$a', "return null;" ) );
wp_clear_scheduled_hook( 'wp_update_plugins' );

?>

<?php 
/**
 * Plugin Name: Enable Major Core Updates
 */
add_filter( 'allow_major_auto_core_updates', '__return_true' );
add_filter( 'auto_update_plugin', '__return_false' );

?>

installed in a special folder /wp-content/mu-plugins and disabled auto-update plugins and core WP

Plugin that disables notifications of  wp-kernel and wp-plugin updates

wordpress

PHP