How to implement locale change by users?

Question

Internationalization and localization

Tasks - a multilingual site. There are 2 .mo files, ru_Ru and fr_FR. If I understand correctly, Wordpress uses the .mo whose index matches the site language index, that is, if the site language is Russian, then fr_FR is ignored and vice versa. How can (and can it?) give users the ability to switch languages?

Answer 1

WPML. Polylang and other multilingual plugins

Answer 2

https://en.wordpress.org/plugins/polylang/
https://en.wordpress.org/plugins/qtranslate-x/
https://en.wordpress.org/plugins/wpglobus/
Each registered user has language settings in their profile.