WPEP Order Index Page by Publish Date

example.php

<?php

// Please ensure that WPEP -> Settings -> Index Page -> Grid Options -> Enforce Ordering Option is Disabled.

add_filter( 'wpep_primary_content_list_args', function($args) {
  $args = [
    'order'       => 'DESC',
    'orderby'     => 'date',
  ];

  return $args;
}, 50000 );