Code snippet that can be used to add more theme suggestions programmatically to forms in drupal 8.
To do that in our custom theme folder in the .theme file we have to add the following hook function: hook_theme_suggestions_HOOK_alter like below:
/**
* @param array $suggestions
* @param array $variables
* @param $hook
*/
function THEMENAME_theme_suggestions_form_alter(array &$suggestions, array &$variables, $hook)
{
if (isset($variables['element']['#form_id'])) {
$suggestions[] = $hook . '__' . $variables['element']['#form_id'];
}
}
