您可以通过调用update_post_meta() 按键为‘_wp_page_template’.

或者在插入帖子时，您可以传递page_template 到wp_insert_post().

请参见：https://developer.wordpress.org/reference/functions/wp_insert_post/#more-information

使用wp_insert_post（）可以添加新帖子并使用现有主题。

  $new_page_id = array(
        \'post_title\'     => \'examplePage\',
        \'post_type\'      => \'custom_post\',
        \'post_name\'      => \'examplePage\',
        \'post_content\'   => \'\',
        \'post_status\'    => \'publish\',
        \'post_author\'    => get_user_by( \'id\', 1 )->user_id,
        \'menu_order\'     => 0,
        // Assign page template
        \'page_template\'  => "/wp-content/themes/test-theme/universal-template.php"


    ); 
    wp_insert_post($new_page_id);