redirect to /wp-admin/edit.php instead of wp_redirect url

You just need to change the second parameter for get_edit_post_link(), which is $context and defaults to display. And that parameter determines how to output the ampersand character (i.e. &), which defaults to being encoded as & (because the default context is that the URL is being displayed, hence the & is encoded).

• When using the URL with redirection, you would want to use the edit (or anything other than display) context:

  $edit_post_link = get_edit_post_link( $order_id, 'edit' );
  wp_redirect( $edit_post_link );
  

• When displaying the URL, you would use the display context:

  $edit_post_link = get_edit_post_link( $order_id, 'display' );
  
  // Or you can simply ignore the second parameter:
  $edit_post_link = get_edit_post_link( $order_id );
  
  var_dump( $edit_post_link ); // & becomes &