If the portal users have logged in by selecting another language, they will get the portal content in that translated language.
The portal users will get the Language Switcher in Before Login & After Login as you have configured.
The portal users will get the ‘Language Switcher’ on the Menu based on the configuration in the ‘Menu’ widget. By clicking on it, they will get the enabled & configured language drop-down list, they can select any language to switch to their desired language.
By clicking on another language, the portal content will load & appear in that language.