How to add new site language in Django admin

I work on a project where we want to have multilingual site. We start with two languages defined in settings.py

LANGUAGES = (
    ("en-us", _("United States")),
    ("cs", _("Czech Republic")),
)

I am not the programmer doing the work but if I understood correctly all we need is to be able to add - for example - French language for the whole website but not via setting.py but Django admin web interface.

LANGUAGES = (
    ("en-us", _("United States")),
    ("cs", _("Czech Republic")),
    ("fr", _("French")),
)

We are using rosetta for translating in Django admin. So I want to use Django admin to add new laguage so it appears in rosetta interface.

Could someone tell me how we can control ( add or remove or disable ) languages from Django admin?

I checked these but did not find the answer

• Adding new site language in Django admin
• How to manage system languages from django admin site?
• https://djangowaves.com/tutorial/multiple-languages-in-Django/
• Add translation for model field using django rosetta
• Adding languages dynamically through Django Admin

from How to add new site language in Django admin