Cannot change header size in register_sidebar function

I am starting with WordPress and this is my first post here, I apologize if it is in the wrong section.

I am working on building a theme using namespaces as a starting point. In my functions.php inside my theme I have the function below to register my sidebar.

The original code came with H2’s and I am changing it to H4’s as in the bold text below. When I refresh my browser the size does not change.

The sidebar is getting called from sidebar.php using the dynamic_sidebar function with the correct name. I just can’t get the size of the headings to change. Am I doing something wrong?

Thank you!

function pro_headphones_wp_widgets_init() {

 register_sidebar(
        array(
'name' => esc_html__( 'Sidebar', 'pro-headphones-wp' ),
'id'   => 'sidebar-1',
'description'   => esc_html__( 'Add widgets here.', 'pro-headphones-wp' ),
'before_widget' => '<section id="%1$s" class="widget %2$s">',
'after_widget'  => '</section>',
'before_title'  => '<h4 class="widget-title">',
'after_title'   => '</h4>',
        )
    );
}

add_action( 'widgets_init', 'pro_headphones_wp_widgets_init' );