Old site:
drush sql-dump
to backup database
New site:
composer create-project drupal-composer/drupal-project:8.x-dev newsitefolder --prefer-dist --no-progress --no-interaction
cd newsitefolder
composer require <all of your modules here, as drupal/whatever>
If running SELinux on CentOS, on others it may be a different context
chcon -R -t httpd_sys_content_rw_t web
$ pwd