01-Template.php

<?php 

namespace View;

class Template
{
  public function render($file, $args=[]) 
  {
      extract($this->data);
      ob_start();
      include($file);
      $content = ob_get_contents();
      ob_end_clean();
      return $content;
  }

}

02-index.php

<?php
$options = new Dompdf\Options();
$options->set('isRemoteEnabled', true);
$options->set('isHtml5ParserEnabled', true);
$options->set('isPhpEnabled', true);

$dompdf = new Dompdf\Dompdf($options);

$template = new View\Template();
$html = $template->render('pages/pdf.php');


$dompdf->loadHtml($html);
$dompdf->setPaper('a4', 'landscape');  

$dompdf->render();
$dompdf->stream("exemplo.pdf", array('Attachment' => 0));