Helper class for modifying WordPress Customizer - https://wptips.dev/simplify-wp-customizer-api

my-customizer.php

<?php

/**
 * Helper class for modifying WordPress Customizer
 */
class MyCustomizer {
  private $customize; // $wp_customize object
  private $section;

  function __construct( $customize ) {
    $this->customize = $customize;
  }

  /**
   * Create section
   * 
   * @param string $name - Name of the section.
   * @param array $args - See https://developer.wordpress.org/reference/classes/wp_customize_section/__construct/
   */
  function add_section( $name, $args = [] ) {
    $args = wp_parse_args( $args, [
      // format title from slug, if not given
      'title' => ucwords( str_replace( ['_', '-'], ' ', $name ) )
    ] );

    $this->customize->add_section( $name, $args );
  }


  
  /**
   * Add setting and control
   * 
   * @param string $name - Setting name
   * @param string $args - Setting args with Control args under the key 'control' - https://developer.wordpress.org/reference/classes/wp_customize_setting/__construct/
   */
  function add_setting( $name, $args ) {
    // Default args
    $args = wp_parse_args( $args, [
      'type' => 'theme_mod',
      'transport' => 'postMessage',
    ] );

    $this->customize->add_setting( $name, $args );

    // Default control args
    $control_args = $args['control'];
    $control_args = wp_parse_args( $control_args, [
      'type' => 'text',
      'label' => $this->to_title( $name ),
      'settings' => $name,
      // in case the section arg is placed inside setting's
      'section' => $args['section'] ?? $control_args['section'] ??
        trigger_error( __( 'MyCustomizer Error: ' . $name . ' setting needs section argument' ) ),
    ] );

    $this->add_control( $name . '_control', $control_args );
  }


  /**
   * Add control to the customizer
   * 
   * @param string $name - Control name
   * @param array $args - Control args - https://developer.wordpress.org/reference/classes/wp_customize_control/__construct/
   */
  private function add_control( $name, $args ) {
    $control = false;

    // Check if the input type is complex
    switch( $args['type'] ) {
      case 'code_editor':
        $args['editor_settings'] = array(
          'codemirror' => array(
            'mode' => $args['code_language'] ?? 'default'
          ),
        );
        $control = new \WP_Customize_Code_Editor_Control( $this->customize, $name, $args );
        break;

      case 'image':
        $control = new \WP_Customize_Image_Control( $this->customize, $name, $args );
        break;

      case 'cropped_image':
        $control = new \WP_Customize_Cropped_Image_Control( $this->customize, $name, $args );
        break;

      case 'color':
        $control = new \WP_Customize_Color_Control( $this->customize, $name, $args );
        break;

      case 'upload':
        $control = new \WP_Customize_Upload_Control( $this->customize, $name, $args );
        break;

      case 'background_image':
        $control = new \WP_Customize_Background_Image_Control( $this->customize, $name, $args );
        break;

      case 'header_image':
        $control = new \WP_Customize_Header_Image_Control( $this->customize, $name, $args );
        break;

      // text | select | radio | checkbox | textarea
      // dropdown-pages | email | url | number | hidden | date
      default:
        break;
    }

    // if has complex control
    if( $control ) {
      $this->customize->add_control( $control );
    } else {
      $this->customize->add_control( $name, $args );
    }
    
  }


  /**
   * Convert slug to titleized case
   */
  private function to_title( $slug ) {
    return ucwords( str_replace( ['_', '-'], ' ', $slug ) );
  }
}