The basic angular i18n package will build separate apps for each language file you provide. If you want to use a language switch with this package, all it will do it route them to the subfolder where the other languages are hosted.

For example, if your english site is at www.example.com and you want a spanish translation, angular i18n will build you a separate app that you can deploy to www.example.com/es. Then, your language picker would simply redirect the user to /es.

If you want to change the language at runtime, you should use a third party library like ngx-translate. You could implement it yourself, but you would be re-inventing the wheel. As well, I don't believe ngx-translate is in maintenance mode, their github page does not mention it.

If you want to build it yourself, consider creating a service to fetch json files for the languages and a pipe to convert the language keys to their translated values.