Load different font depending on language of page

Maybe to implement the task (a different font for the menu) - a separate template with a class for menu items or can it display a different header based on the version of the site language?

I understand that I need to work through twig files, but I don’t fully understand how to reconnect them. Ok, I copied the file modular.html.twig and renamed it to modular.en.html.twig
In this file for navigation -li- I add some class and set the font-family through css styles.
But how now to connect all this to the English version of the site in order to display the menu with a new font-family?

You could just load additional CSS depending on language, which would override the default theme font