Get child pages of a page in WordPress

custom.php

<?php
 
$args = array(
    'post_type'      => 'page', //write slug of post type
    'posts_per_page' => -1,
    'post_parent'    => '26', //place here id of your parent page
    'order'          => 'ASC',
    'orderby'        => 'menu_order'
 );
 
 
$childrens = new WP_Query( $args );
 
if ( $childrens->have_posts() ) : ?>
 
    <?php while ( $childrens->have_posts() ) : $childrens->the_post(); ?>
 
        <div class="children" id="child-<?php the_ID(); ?>">
 
            <h2><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>
 
            <p><?php the_content(); ?></p>
 
        </div>
 
    <?php    endwhile; 
            endif; 
        wp_reset_query(); 
    ?>