We have existing app we support in english language, we enhanced app to chinese language, But we stuck with support for
Also its app without lang in user_metadata and using same App in Auth) to support both english and chinese language, But deployed as seperate url
I’d recommend looking into using the New Universal Login Experience, which can read the Accept-Language HTTP header natively, provided it is one of the languages Auth0 supports (and has been enabled in your tenant’s settings):
You can further tweak what the text says using the Text Customisation API for each language you wish to support.
For the email templates, this isn’t currently possible ‘out of the box’ AFAIK, but you can use rules to store a user’s preferred language into their metadata, and then use liquid syntax to alter your email’s contents based on the user’s relevant metadata field: