How can I include Google Structured Data via a module?
There is a Drupal 8 module works tandem with the Metatag module: Schema.org Metatag

From the module description: 


  This project extends Drupal's Metatag module to display structured data as JSON LD in the head of web pages. Read more about Schema.org, JSON LD, and how this module works in an article on Lullabot.com, Create SEO Juice From JSON LD Structured Data in Drupal.