Add days or weeks to order date with proper locale translation and formatting

Here's the similar code that we can use

<?php $twoWeeksDate = date('m/d/y', strtotime('+2 weeks', strtotime($this->getPdfHelper()->getSalesObject()->getCreatedAt()))); ?>
 
<?php
    $twoWeeksDate = Mage::helper('core')->formatDate($twoWeeksDate, 'medium', false);
?>
 
<?php echo $this->getPdfHelper()->getTranslatedString('2 weeks date','pdfcustomiser')?>: <?php echo $twoWeeksDate ?><br/>