Try something like below
1. if the html version used is html5, then try this
<input type="date" name="from">
<input type="date" name="to">
2. or change the date format in php like
<?php
date_default_timezone_set('Asia/Calcutta');
$date = new DateTime('2018-01-31');
$new_date = $date->format('d/m/Y');
echo $new_date;
?>