apply control saves your settings. You can set the
reload control property to true in order to trigger a builder reload after the “Apply” button has been clicked. We use it in the builder for settings like the template “Populate Content” or the “SEO” page settings.
$this->controls['apply'] = [ 'group' => 'template-preview', 'type' => 'apply', 'reload' => true, 'label' => esc_html__( 'Apply preview', 'bricks' ), ];