In macOS there appear words that are underlined in red if the spelling is wrong. However, I started to learn French and only found that French words that are spelled correctly have he red underlines because there are no such words in English.
Is it possible not to apply the spelling check on French words? I added French on the Language and Region setting on System Preferences but still have the underlines...
Here is the result of adding Français to the list.
But the preferences on text at keyboard looks like the following:
The relevant item is in the middle and it reads as Based on languages spell automatically.
And French words still have the underlines.
This is on Note.app and on macOS 10.14.3.