app/Config/Embed.php

+<?php
+
+declare(strict_types=1);
+
+namespace Config;
+
+use CodeIgniter\Config\BaseConfig;
+
+class Embed extends BaseConfig
+{
+    /**
+     * --------------------------------------------------------------------------
+     * Embeddable player config
+     * --------------------------------------------------------------------------
+     */
+    public int $width = 485;
+
+    public int $height = 112;
+}

app/Config/ForeignCharacters.php

 <?php
 
+declare(strict_types=1);
+
 namespace Config;
 
-class ForeignCharacters extends \CodeIgniter\Config\ForeignCharacters
+use CodeIgniter\Config\ForeignCharacters as BaseForeignCharacters;
+
+/**
+ * @immutable
+ */
+class ForeignCharacters extends BaseForeignCharacters
 {
 }