Hi!
Here are some things you can try:
Add system-wide keyboard language
In Settings > General > Keyboards, click "Add New Keyboard." Now add the French keyboard.
When you type your email: on your software keyboard, hold the emoji button and switch to the French keyboard. Spell checking should be in French now.
Change only Outlook app to French
There is an option to change an entire app into another language. To do that, follow these steps:
1: Make sure you have French set as a secondary system language. Go into Settings > General > Language & Region.
- Check under "Preferred Languages." If French is there, continue to step 2. Otherwise, read below.
- Click "Add Language," select French. When it asks you whether you want to change the primary language to French, select "Use English" (or whichever language your device is set to
2: Change language of the app itself in your iPad system settings.
- On iPadOS 17 and earlier, on the homepage of the settings app, scroll down until you see Outlook. Click on that, and change the language to French
- iPadOS 18, Settings > Apps > Outlook. Then change the language to French.
TL;DR:
You can try to a) change your keyboard to a French keyboard or b) change the language of the entire outlook app.