diff --git a/forms.rst b/forms.rst
index c5e41222104..b6c63773452 100644
--- a/forms.rst
+++ b/forms.rst
@@ -345,13 +345,13 @@ can set this option to generate forms compatible with the Bootstrap 4 CSS framew
     .. code-block:: php
 
         // config/packages/twig.php
-        $container->loadFromExtension('twig', [
-            'form_themes' => [
-                'bootstrap_4_layout.html.twig',
-            ],
+        use Symfony\Config\TwigConfig;
+
+        return static function (TwigConfig $twig) {
+            $twig->formThemes(['bootstrap_4_layout.html.twig']);
 
             // ...
-        ]);
+        };
 
 The :ref:`built-in Symfony form themes <symfony-builtin-forms>` include
 Bootstrap 3 and 4 as well as Foundation 5 and 6. You can also
@@ -627,11 +627,11 @@ these new messages set the ``legacy_error_messages`` option to ``false``:
     .. code-block:: php
 
         // config/packages/framework.php
-        $container->loadFromExtension('framework', [
-            'form' => [
-                'legacy_error_messages' => false,
-            ],
-        ]);
+        use Symfony\Config\FrameworkConfig;
+
+        return static function (FrameworkConfig $framework) {
+            $framework->form()->legacyErrorMessages(false);
+        };
 
 Other Common Form Features
 --------------------------
diff --git a/routing.rst b/routing.rst
index 9aad1ac3c58..487d2ecc587 100644
--- a/routing.rst
+++ b/routing.rst
@@ -2508,12 +2508,11 @@ The solution is to configure the ``default_uri`` option to define the
     .. code-block:: php
 
         // config/packages/routing.php
-        $container->loadFromExtension('framework', [
-            'router' => [
-                // ...
-                'default_uri' => "https://example.org/my/path/",
-            ],
-        ]);
+        use Symfony\Config\FrameworkConfig;
+
+        return static function (FrameworkConfig $framework) {
+            $framework->router()->defaultUri('https://example.org/my/path/');
+        };
 
 .. versionadded:: 5.1
 
diff --git a/serializer.rst b/serializer.rst
index 980bf5708ab..8cae58c5838 100644
--- a/serializer.rst
+++ b/serializer.rst
@@ -259,12 +259,11 @@ value:
     .. code-block:: php
 
         // config/packages/framework.php
-        $container->loadFromExtension('framework', [
-            // ...
-            'serializer' => [
-                'name_converter' => 'serializer.name_converter.camel_case_to_snake_case',
-            ],
-        ]);
+        use Symfony\Config\FrameworkConfig;
+
+        return static function (FrameworkConfig $framework) {
+            $framework->serializer()->nameConverter('serializer.name_converter.camel_case_to_snake_case');
+        };
 
 Going Further with the Serializer
 ---------------------------------
diff --git a/session.rst b/session.rst
index 5a3fb69c09b..8f3fba95b30 100644
--- a/session.rst
+++ b/session.rst
@@ -55,18 +55,20 @@ sessions, check their default configuration:
     .. code-block:: php
 
         // config/packages/framework.php
-        $container->loadFromExtension('framework', [
-            'session' => [
+        use Symfony\Config\FrameworkConfig;
+
+        return static function (FrameworkConfig $framework) {
+            $framework->session()
                 // enables the support of sessions in the app
-                'enabled' => true,
+                ->enabled(true)
                 // ID of the service used for session storage
                 // NULL means that Symfony uses PHP default session mechanism
-                'handler_id' => null,
+                ->handlerId(null)
                 // improves the security of the cookies used for sessions
-                'cookie_secure' => 'auto',
-                'cookie_samesite' => 'lax',
-            ],
-        ]);
+                ->cookieSecure('auto')
+                ->cookieSamesite('lax')
+            ;
+        };
 
 Setting the ``handler_id`` config option to ``null`` means that Symfony will
 use the native PHP session mechanism. The session metadata files will be stored
@@ -112,13 +114,15 @@ session metadata files:
     .. code-block:: php
 
         // config/packages/framework.php
-        $container->loadFromExtension('framework', [
-            'session' => [
+        use Symfony\Config\FrameworkConfig;
+
+        return static function (FrameworkConfig $framework) {
+            $framework->session()
                 // ...
-                'handler_id' => 'session.handler.native_file',
-                'save_path' => '%kernel.project_dir%/var/sessions/%kernel.environment%',
-            ],
-        ]);
+                ->handlerId('session.handler.native_file')
+                ->savePath('%kernel.project_dir%/var/sessions/%kernel.environment%')
+            ;
+        };
 
 Check out the Symfony config reference to learn more about the other available
 :ref:`Session configuration options <config-framework-session>`. You can also
diff --git a/templates.rst b/templates.rst
index 9f1f5233b34..af18a438484 100644
--- a/templates.rst
+++ b/templates.rst
@@ -824,10 +824,12 @@ template fragments. Configure that special URL in the ``fragments`` option:
     .. code-block:: php
 
         // config/packages/framework.php
-        $container->loadFromExtension('framework', [
+        use Symfony\Config\FrameworkConfig;
+
+        return static function (FrameworkConfig $framework) {
             // ...
-            'fragments' => ['path' => '/_fragment'],
-        ]);
+            $framework->fragments()->path('/_fragment');
+        };
 
 .. caution::
 
@@ -1043,15 +1045,16 @@ the ``value`` is the Twig namespace, which is explained later:
     .. code-block:: php
 
         // config/packages/twig.php
-        $container->loadFromExtension('twig', [
+        use Symfony\Config\TwigConfig;
+
+        return static function (TwigConfig $twig) {
             // ...
-            'paths' => [
-                // directories are relative to the project root dir (but you
-                // can also use absolute directories)
-                'email/default/templates' => null,
-                'backend/templates' => null,
-            ],
-        ]);
+
+            // directories are relative to the project root dir (but you
+            // can also use absolute directories)
+            $twig->path('email/default/templates', null);
+            $twig->path('backend/templates', null);
+        };
 
 When rendering a template, Symfony looks for it first in the ``twig.paths``
 directories that don't define a namespace and then falls back to the default
@@ -1098,13 +1101,14 @@ configuration to define a namespace for each template directory:
     .. code-block:: php
 
         // config/packages/twig.php
-        $container->loadFromExtension('twig', [
+        use Symfony\Config\TwigConfig;
+
+        return static function (TwigConfig $twig) {
             // ...
-            'paths' => [
-                'email/default/templates' => 'email',
-                'backend/templates' => 'admin',
-            ],
-        ]);
+
+            $twig->path('email/default/templates', 'email');
+            $twig->path('backend/templates', 'admin');
+        };
 
 Now, if you render the ``layout.html.twig`` template, Symfony will render the
 ``templates/layout.html.twig`` file. Use the special syntax ``@`` + namespace to