Hi @quanlm!
The language of the widgets can generally be controlled either by the user’s browser language preference or by the application sending the ui_locales parameter with the required language. The language should also be enabled in the Auth0 Dashboard settings. Have you enabled the desired languages in your tenant? The supported languages are at the bottom of the Settings > General page in the Auth0 Dashboard. See Universal Login Internationalization for more information.
Additionally, here is an article that may be of help to you:
Please let me know if you have any additional questions!
Best,
Mary Beth