can there be two body templates to send back a new page?

I am creating a contact page. I have created templates to display the header, contact form, and footer. When a user's email is sent how can I send back a page to the user? I will use templating for the success page.

<?php
 /* *********************************************
   * mustache library
  * ********************************************* */

  require_once 'mustache/mustache/src/Mustache/Autoloader.php';
  Mustache_Autoloader::register();

  $mustache = new Mustache_Engine;

  $header = file_get_contents('templates/header.html');
  $body = file_get_contents('templates/emailform.html');
  $footer = file_get_contents('templates/footer.html');

  $header_data = ["pagetitle" => "Contact"];

  $footer_data = [
      "localtime" => date('l jS \of F Y h:i:s A'),
      "footertitle" => "Contact"];


  echo $mustache->render($header, $header_data) . PHP_EOL;
  echo $mustache->render($body) . PHP_EOL;
  echo $mustache->render($footer, $footer_data) . PHP_EOL;

 function successpage() {


        $body = file_get_contents('templates/success_contact.html');
 }

 function failurepage() {
        $body = file_get_contents('templates/failure_contact.html');
 }

source https://stackoverflow.com/questions/71414105/can-there-be-two-body-templates-to-send-back-a-new-page