Change “Howdy” text in the admin bar

function snipjar_change_howdy( $wp_admin_bar ) {

	// Edit the line below to set what you want the admin bar to display intead of "Howdy,".
	$new_howdy = 'Welcome,';

	$my_account = $wp_admin_bar->get_node( 'my-account' );
	$wp_admin_bar->add_node(
		array(
			'id'    => 'my-account',
			'title' => str_replace( 'Howdy,', $new_howdy, $my_account->title ),
		)
	);
}

add_filter( 'admin_bar_menu', 'snipjar_change_howdy', 25 );

Change admin panel footer text

add_filter(
	'admin_footer_text',
	function ( $footer_text ) {
		$footer_text = 'Brought to you by by <a href="https://www.snipjar.com" target="_blank" rel="noopener">Snipjar</a>';
		return $footer_text;
	}
);

Set a minimum word count for posts

function wpcode_snippet_publish_min_words( $post_id, $post ) {
	$word_count = 100;

	if ( str_word_count( $post->post_content ) < $word_count ) {
		wp_die(
			sprintf(
				// Translators: placeholder adds the minimum number of words.
				esc_html__( 'The post content is below the minimum word count. Your post needs to have at least %d words to be published.' ),
				absint( $word_count )
			)
		);
	}
}

add_action( 'publish_post', 'wpcode_snippet_publish_min_words', 9, 2 );

Disable attachment pages

add_action(
	'template_redirect',
	function () {
		global $post;
		if ( ! is_attachment() || ! isset( $post->post_parent ) || ! is_numeric( $post->post_parent ) ) {
			return;
		}

		// Does the attachment have a parent post?
		// If the post is trashed, fallback to redirect to homepage.
		if ( 0 !== $post->post_parent && 'trash' !== get_post_status( $post->post_parent ) ) {
			// Redirect to the attachment parent.
			wp_safe_redirect( get_permalink( $post->post_parent ), 301 );
		} else {
			// For attachment without a parent redirect to homepage.
			wp_safe_redirect( get_bloginfo( 'wpurl' ), 302 );
		}
		exit;
	},
	1
);

Disable WordPress REST API

add_filter(
	'rest_authentication_errors',
	function ( $access ) {
		return new WP_Error(
			'rest_disabled',
			__( 'The WordPress REST API has been disabled.' ),
			array(
				'status' => rest_authorization_required_code(),
			)
		);
	}
);

Completely disable comments for all post types, in the admin and the frontend

add_action('admin_init', function () {
    // Redirect any user trying to access comments page
    global $pagenow;
    
    if ($pagenow === 'edit-comments.php') {
        wp_safe_redirect(admin_url());
        exit;
    }

    // Remove comments metabox from dashboard
    remove_meta_box('dashboard_recent_comments', 'dashboard', 'normal');

    // Disable support for comments and trackbacks in post types
    foreach (get_post_types() as $post_type) {
        if (post_type_supports($post_type, 'comments')) {
            remove_post_type_support($post_type, 'comments');
            remove_post_type_support($post_type, 'trackbacks');
        }
    }
});

// Close comments on the front-end
add_filter('comments_open', '__return_false', 20, 2);
add_filter('pings_open', '__return_false', 20, 2);

// Hide existing comments
add_filter('comments_array', '__return_empty_array', 10, 2);

// Remove comments page in menu
add_action('admin_menu', function () {
    remove_menu_page('edit-comments.php');
});

// Remove comments links from admin bar
add_action('admin_bar_menu', function () {
    remove_action('admin_bar_menu', 'wp_admin_bar_comments_menu', 60);
}, 0);

Disable automatic updates emails

add_filter( 'auto_core_update_send_email', '__return_false' );
add_filter( 'auto_plugin_update_send_email', '__return_false' );
add_filter( 'auto_theme_update_send_email', '__return_false' );