Hi,
<script type="text/javascript">
require(['jquery', 'mage/calendar'], function($){
$("#input_date").calendar({
buttonText: "<?php echo __('Date') ?>",
dateFormat: "d/m/yy",
minDate : 0
});
});
</script>
Or you can change date format from PHP using the following code. Reference
$created_at = \DateTime::createFromFormat('j/n/Y', $created_at)->format("l");
Kind regards,
Thomas