find last sunday and -1 week in drupal 8

find last sunday and -1 week in drupal 8

use Drupal\Component\Datetime\DateTimePlus;

$format = "D";
$current_date = new DateTimePlus();
$current_timezone = date_default_timezone_get();
date_default_timezone_set("UTC");
$current_day = $current_date->format($format, ['timezone' => drupal_get_user_timezone()]);

$lastweek = 'last Sunday -1 week';
$dateformat = 'Y-m-d\TH:i:s';
if ($current_day != "Sun") {
   $lastsundaydate = new DateTimePlus($lastweek);
   $lastsundaydate = $lastsundaydate->format($dateformat, ['timezone' => drupal_get_user_timezone()]);
}
date_default_timezone_set($current_timezone);
dpm($lastsundaydate);