For a few days I began to rewarm my old acquaintance to a woman who lives in Algeria. With this woman I only speak French. I inhere in using the correct letters. The French é or è or etc. does not work with my German Google keyboard layout.
I found the solution:
You click onto the letter „e“ then you must press it and a new field appears. In this field there a lot of special characters. Then you must slip with your finger to your desired special letter and then you let loose it and the special character appears in your text message (not only in Whatsapp).
But the French special characters ê or ç does not work with it. The Spanish ñ as ¿ and ¡ are working.
I saw some Scandinavian special characters, too.
I have tested it with Android 7.