Create custom page in wordpress

// used for linking the php code to wordpress
<?php
/**
Template Name: Chatbot Php
*/
?>

// Update the page number which you have noted above in my case it is 16251
<?php
if(is_page(16251)) {
get_header('page'); // You can also change the header for the this page, 
If you want to know how to create a custom header and sidebar for a page please check my blog on
 “How to create custom header and sidebar for different page and post”
}
else {
get_header(); // You can use header which you are normally using for your site
}
wp_head();
?>

Note the below can be changed or edited as per your theme and design,
// Get sidebar position in my case it is right.
<?php
$ht_page_sidebar = null;
$ht_page_sidebar = get_post_meta( get_the_ID(), 'st_post_sidebar', true );
if ($ht_page_sidebar == '') {
$ht_page_sidebar = 'sidebar-right';
}
?>

// Page Header
<!-- #primary -->
<div id="primary" class="<?php echo esc_attr($ht_page_sidebar); ?> clearfix">
<!-- .ht-container -->
<div class="ht-container">
<!-- #content -->
<section id="content" role="main">
<!-- #page-header -->
<header id="page-header" class="clearfix">
<h1 class="page-title"><?php the_title(); ?></h1> <!-- This will output the title of the page -->
//Displays the featured images
<?php
if ( has_post_thumbnail() && ! post_password_required() ) : ?>
<div class="entry-thumbnail">
<?php the_post_thumbnail(); ?> // output featured images in our theme
</div>
<?php endif; ?>
</header>
<!-- /#page-header -->

<!-- Loop checking check if the loop has returned any posts -->
<?php while ( have_posts() ) : the_post(); ?>
<article id="post-<?php the_ID(); ?>" <?php post_class(); ?>> <!-- set up the content so we can use template tags like the_title() -->
<div class="entry-content">
<?php
the_content(); // output the post content.
wp_link_pages( array( 'before' => '<div class="page-links"><strong>' . __( 'Pages:', 'knowhow' ) .'</strong>', 'after' => '</div>' ) );
?>
</div>

<?php if (is_page() && has_tag()) { ?> <!-- Checking if the post have tags -->
<div class="tags">
<?php
the_tags( '<strong> '. __( 'Tagged:', 'knowhow' ) .' </strong>', '', ''); ?> <!-- Outputs the tags, here knowhow is theme name -->
</div>
<?php } ?>
</article>

<?php // If comments are open or we have at least one comment, load up the comment template
if ( comments_open() || '0' != get_comments_number() )
comments_template( '', true );
endwhile; // end of the loop.
?>

</section>
<!-- #content -->
<!-- Display the sidebar -->
<?php
if ($ht_page_sidebar != 'sidebar-off') {
?>
<?php get_sidebar(); ?> <!-- Action hook which will display the sidebar -->
<?php } ?>

</div>
<!-- .ht-container -->
</div>
<!-- #primary -->

<?php get_footer(); ?> <!-- Action hook which will display the footer -->