$webform = DrupalwebformEntityWebform::load('high_level_design');

$form_state = new FormState();
$form_state->setRebuild();
$form = Drupal::formBuilder()->buildForm($webform, $form_state);

'Drupalcustom_moduleFormCustomModuleForm'

'DrupalwebformEntityWebformwebform-submission-high_level_design-form'

'DrupalwebformEntityWebformwebform-submission-high_level_design-form::class'