WP_Widget_Area_Customize_Control example

$control = new WP_Sidebar_Block_Editor_Control(
                            $this->manager,
                            $setting_id,
                            array(
                                'section'     => $section_id,
                                'sidebar_id'  => $sidebar_id,
                                'label'       => $section_args['title'],
                                'description' => $section_args['description'],
                            )
                        );
                    } else {
                        $control = new WP_Widget_Area_Customize_Control(
                            $this->manager,
                            $setting_id,
                            array(
                                'section'    => $section_id,
                                'sidebar_id' => $sidebar_id,
                                'priority'   => count( $sidebar_widget_ids ), // place 'Add Widget' and 'Reorder' buttons at end.                             )
                        );
                    }

                    $this->manager->add_control( $control );