以下是我遵循的流程。

第1步。指定要放置页面的页面的slug。为了避免将其硬编码到插件中，我添加了一个设置选项来存储页面的slug。因此，如果我更改页面，我只需在设置页面中指定新页面的slug。

function my_plugin_settings_page() {
//Add a settings page for this plugin to the Settings menu.
add_options_page( \'My Plugin Settings\', \'My Settings\', \'manage_options\', \'my-plugin-settings\', \'display_my_plugin_settings\' );
}


function display_my_plugin_settings{?>
<div class="wrap">

<h2><?php echo esc_html(get_admin_page_title()); ?></h2>
<?php 
$options = get_option(\'my-plugin\');
settings_fields(\'my-plugin\');
?>
    <form method="post" name="my-plugin-settings" action="options.php">
    <fieldset>
        <legend class="screen-reader-text"><span><?php _e(\'Signup Page\', \'my-plugin\'); ?></span></legend>
        <label for="my-plugin-signup">
            <?php echo home_url(\'/\');?><input type="text" id="my-plugin-agent_signup" name="my-plugin[signup]" value="<?php echo $options[\'signup\'];?>"/>
            <span><?php esc_attr_e(\'Signup Page\', \'my-plugin\'); ?></span><br>
            <span class="description"><?php esc_attr_e(\'The signup form will be added to the end of this page\', \'my-plugin\'); ?></span>
        </label>
    </fieldset>

<?php submit_button(\'Save\', \'primary\',\'submit\', TRUE); ?>
</form>
</div>
<?php}

add_action( \'admin_menu\', \'my_plugin_settings_page\' );

public function signup_template($page_template) {
        $options = get_option(\'my-plugin\'); //get plugin options
         if (is_page( $options[\'signup\'] )) {
              $page_template = dirname( __FILE__ ) . \'/public/partials/registrationform.php\'; 
              //change the template if the page is the one specified
         }
         return $page_template;
    } 

add_filter( \'page_template\', \'user_profile_template\', 11 ); //filter hook to change the page template