To install a module you just run composer require drupal/<modulename> i.e. composer require drupal/token

You can also specify a version composer require 'drupal/<modulename>:<version> i.e. composer require 'drupal/token:^1.5'

Note the quotes when specifying a version.

Typical examples:

composer require drupal/admin_toolbar
composer require drupal/colorbox
composer require drupal/ctools

Note: the opposite to composer require is composer remove i.e. composer remove drupal/xmlsitemap

Enabling Modules Using Drush

Change to the Drush directory cd vendor/bin and use drush en -y <modulename> to enable the modules. The "-y" automatically selects "yes" when asked if you want to install dependencies.

Typical examples:

drush en -y admin_toolbar
drush en -y colorbox
drush en -y ctools

Note: the opposite to drush en -y is drush pm:uninstall i.e. drush pm:uninstall xmlsitemap

Some of the above require code libraries (i.e. colorbox). Sometimes there are Drush commands so revisit the module page to check.

drush colorbox-plugin (adds the JS code to the libraries folder).