Sort all new messages according to the date when message has been received by the users

I want to sort all the messages on top that has been received by the users according to the date when the message has been sent to the users

here is the code:
`

<?php
            if ($_SESSION['role_as'] === '1') {
              $query = " SELECT u.fname, u.lname, u.unique_id, shop.name as shopname FROM user u
              join tattooshops shop on shop.id=u.shopid 
              WHERE unique_id= '".$_SESSION['unique_id']."' ";
            } else {
              $query = " SELECT fname, lname, unique_id FROM user WHERE unique_id= '".$_SESSION['unique_id']."' ";
            }

            $query_run = mysqli_query($con, $query);
            $check_user = mysqli_num_rows($query_run) > 0;

            if ($check_user) {
              while ($row = mysqli_fetch_array($query_run)) {
                if ($_SESSION['role_as'] === '1') {
                  $userName = $row['shopname'];
                } else {
                  $userName = $row['fname'] ." ". $row['lname'];
                }
                echo '<div class="details">';
                  echo '<span>' . "Messages for " . $userName .'</span>';
                echo '</div>';
              }
            }
          ?>

`

this is the image that the message is not arranged accordingly:
enter image description here

I’ll expect that all the messages who are currently receiving according to date will sort on top