wp-extend-recent-posts-widget.php

<?php
add_filter(
    'widget_posts_args',
    function ( $args, $instance ) {

	    if ( isset( $instance['cpt'] ) ) {
		    $args['post_type'] = $instance['cpt'];
        }

	    if ( isset( $instance['order_by'] ) ) {
		    $args['orderby'] = $instance['order_by'];
	    }

        return $args;
    },
    10,
    2
);

add_filter(
    'widget_update_callback',
    function ( $instance, $new_instance, $old_instance, WP_Widget $widget ) {

	    if ( ! $widget instanceof WP_Widget_Recent_Posts ) {
		    return $instance;
	    }

	    $instance['cpt']      = $new_instance['cpt'];
	    $instance['order_by'] = $new_instance['order_by'];

	    return $instance;
    },
    10,
    4
);
add_action(
	'in_widget_form',
	function ( WP_Widget $widget, $form, $instance ) {

        if ( ! $widget instanceof WP_Widget_Recent_Posts ) {
            return;
        }
		
	$post_types = get_post_types( [ 'public' => true ], 'objects' );

        if ( ! $post_types ) {
            return;
        }

        $order_fields = [
            'post_date'  => 'Дата',
            'post_title' => 'Название',
            'post_name'  => 'Слаг',
            'rand'       => 'Случайно',
        ];

	$cpt      = $instance['cpt'] ?? 'post';
	$order_by = $instance['order_by'] ?? 'post_date';
   	?>
        <p>
            <label for="<?php echo $widget->get_field_id('cpt'); ?>">Тип записей:</label>
            <select id="<?php echo $widget->get_field_id('cpt'); ?>" name="<?php echo $widget->get_field_name('cpt'); ?>">
                <?php foreach ( $post_types as $post_type ) : ?>
                    <option value="<?php echo esc_attr( $post_type->name ); ?>"<?php selected( $cpt, $post_type->name ); ?>><?php echo esc_html( $post_type->label ); ?></option>
                <?php endforeach; ?>
            </select>
        </p>

        <p>
            <label for="<?php echo $widget->get_field_id('order_by'); ?>">Сортировать по полю:</label>
            <select id="<?php echo $widget->get_field_id('order_by'); ?>" name="<?php echo $widget->get_field_name('order_by'); ?>">
		<?php foreach ( $order_fields as $name => $label ) : ?>
                    <option value="<?php echo esc_attr( $name ); ?>"<?php selected( $order_by, $name ); ?>><?php echo esc_html( $label ); ?></option>
		<?php endforeach; ?>
            </select>
        </p>
        <?php
	},
	10,
	3
);