我知道这是一个古老的问题，已经有了答案，但这不是我一直在寻找的解决方案。如果其他人正在搜索将所有WordPress模板文件移动到子文件夹的方法，请添加另一个选项。找到这个code for changing the default folder for WordPress template files 在Reddit上进行了一些小的调整。此代码可以放置在函数中。主题或子主题的php。

/**
 * Tell WordPress that we have moved default template files to the page-templates folder.
 * Based on code from: https://www.reddit.com/r/Wordpress/comments/ffhjvw/moving_wordpress_theme_template_files_to/
 *
 * Related posts with other solutions:
 * https://stackoverflow.com/questions/60589503/moving-wordpress-theme-template-files-to-subdirectory
 * https://wordpress.stackexchange.com/questions/17385/custom-post-type-templates-from-plugin-folder
 * https://wordpress.stackexchange.com/questions/291725/store-page-template-files-in-a-subfolder
 * https://wordpress.stackexchange.com/questions/312159/how-to-move-page-template-files-like-page-slug-php-to-a-sub-directory/312611#312611
 * 
 * Template hierarchy info: 
 * https://developer.wordpress.org/reference/hooks/type_template_hierarchy/
 * https://core.trac.wordpress.org/browser/tags/5.8.1/src/wp-includes/template.php
 * https://developer.wordpress.org/themes/basics/organizing-theme-files/#page-templates-folder
 *
 * @param array $templates A list of candidates template files.
 * @return string Full path to template file.
 */
function change_template_path($templates) {

  // The custom sub-directory for page templates in your theme. 
  $custom_sub_dir = \'page-templates\';

  // Don\'t use the custom template directory in unexpected cases.
  if(empty($templates) || ! is_array($templates)) {
    return $templates;
  }

  $page_template_id = 0;
  $count = count( $templates);
  if($templates[0] === get_page_template_slug()) {
    // if there is a custom template, then our page-{slug}.php template is at the next index
    $page_template_id = 1;
  }

  // The last one in $templates is page.php, single.php, or archives.php depending on the type of template hierarchy being read.
  // Paths of all items starting from $page_template_id will get updated
  for($i = $page_template_id; $i < $count ; $i++) {
    $templates[$i] = $custom_sub_dir . \'/\' . $templates[$i];
  }

  return $templates;
}

// Add filters to override the path for each WP template hierarchy.
// These are all the template hierarchy filters. You should probably only override the ones you need.
add_filter(\'404_template_hierarchy\', \'change_template_path\');
add_filter(\'archive_template_hierarchy\', \'change_template_path\');
add_filter(\'attachment_template_hierarchy\', \'change_template_path\');
add_filter(\'author_template_hierarchy\', \'change_template_path\');
add_filter(\'category_template_hierarchy\', \'change_template_path\');
add_filter(\'date_template_hierarchy\', \'change_template_path\');
add_filter(\'embed_template_hierarchy\', \'change_template_path\');
add_filter(\'frontpage_template_hierarchy\', \'change_template_path\');
add_filter(\'home_template_hierarchy\', \'change_template_path\');
// If you override the index hierarchy, be sure to add an index.php template in your custom template folder.
add_filter(\'index_template_hierarchy\', \'change_template_path\'); 
add_filter(\'page_template_hierarchy\', \'change_template_path\');
add_filter(\'paged_template_hierarchy\', \'change_template_path\');
add_filter(\'privacypolicy_template_hierarchy\', \'change_template_path\');
add_filter(\'search_template_hierarchy\', \'change_template_path\');
add_filter(\'single_template_hierarchy\', \'change_template_path\');
add_filter(\'singular_template_hierarchy\', \'change_template_path\');
add_filter(\'tag_template_hierarchy\', \'change_template_path\');
add_filter(\'taxonomy_template_hierarchy\', \'change_template_path\');