Cant find a way to access the CiviCRM $form object in Drupal
@soupmagnet Welcome to CiviCRM world!

You can alter the form elements or add your own form element to any CiviCRM forms using CiviCRM buildForm hook. The documentation provided good example on how to do it. Please implement this hook either in CiviCRM extension or Drupal module.

HTH

Pradeep