The Micro Site module allows you to set up a Drupal web factory, from a single Drupal 8 instance, to power a multitude of sites, of a different nature if necessary. Micro Site provides a new content entity that allows you to customize these different site types at will, using the APIs available on Drupal 8, and modify their behavior according to business needs.
Drupal 8 is a tool designed to meet the needs of the most ambitious web projects. We hear a lot about the notions of headless, API first, decoupling, etc. that resolutely allow solid architectures for ambitious projects. But this does not mean that Drupal 8 no longer propels more traditional, and sometimes even much less ambitious sites: simple, small, and even large, websites, but for which we want to benefit from the modularity, flexibility and robustness of Drupal.