You can use locale with both the initial installation and upgrade options.
locale designates the locale packages you want to install or add when upgrading for the specified locale_name. The locale_name values are the same as those values that are used for the $LANG environment variable. International Language Environments Guide contains a list of valid locale values.
When you use the locale keyword, consider the following:
If you have preconfigured a default locale, the locale is automatically installed. The English language packages are installed by default.
You can specify a locale keyword for each locale you need to add to a system.