How to create new title and its description inside a section in WP Customizer?

To add a new title and its description inside a section in the WordPress Customizer, you’ll need to add a custom_control for this purpose. You can create a custom control class for displaying the title and description, and then add an instance of this control to your section.

Here’s how you can do it:

1. Create a Custom Control Class:
   First, create a custom control class to handle the display of your title and description.

if ( class_exists( 'WP_Customize_Control' ) ) {
    class My_Custom_Title_Control extends WP_Customize_Control {
        public $type="custom_title";
        public $description = '';

        public function render_content() {
            ?>
            <h2><?php echo esc_html( $this->label ); ?></h2>
            <?php if ( ! empty( $this->description ) ) : ?>
                <p><?php echo esc_html( $this->description ); ?></p>
            <?php endif; ?>
            <?php
        }
    }
}

2. Add the Custom Control to Your Section:
   In your theme’s functions.php file or wherever you are adding your customizer settings, add the following code to include the new control:

function mytheme_customize_register( $wp_customize ) {
    // Assuming your section is already created and named 'my_custom_section'
    $wp_customize->add_section( 'my_custom_section', array(
        'title'       => __( 'My Custom Section', 'mytheme' ),
        'priority'    => 30,
    ));

    // Add the custom title control
    $wp_customize->add_setting( 'my_custom_title_setting', array(
        'sanitize_callback' => 'wp_kses_post', // Sanitize the content if needed
    ));

    $wp_customize->add_control( new My_Custom_Title_Control( $wp_customize, 'my_custom_title', array(
        'label'       => __( 'General Settings', 'mytheme' ),
        'description' => __( 'This is a small description of the General Settings section.', 'mytheme' ),
        'section'     => 'my_custom_section',
        'settings'    => 'my_custom_title_setting',
        'priority'    => 1,
    )));
}
add_action( 'customize_register', 'mytheme_customize_register' );