2025 Vuetify 3.10+

"vite.config.js":

vuetify({
  styles: {
    configFile: 'src/styles/settings.scss',
  },
})

"src/styles/settings.scss":

@use 'vuetify/settings' with (
    $body-font-family: ('Arial', sans-serif),
);

Source: https://vuetifyjs.com/en/features/sass-variables/