There are several ways to install a Dupal 8 site instance with Composer, but the following includes the automated options that I prefer most.
$ composer create-project drupal-composer/drupal-project:8.x-dev [[[ /path/to/site/root/parent ]]] --stability dev --no-interaction[[[ /path/to/site/root/parent ]]] = the path to the parent directory above the web/docroot of the site.
| feature | drupal-composer/drupal-project |
|---|---|
| directory structure | web is subdir |
| installer-paths config | yes |
| repositories config | yes |
| includes drush | yes |
| includes drupal console | yes |
References: