Arabic (Feminine) display language is currently only available on web.
Go to your device’s Settings feature and tap General.
Tap Language&Region.
Tap iPhone Language to change your primary language, or Other languages to add a language.
Go back to your device's Settings until you see the >x< for iOS app and tap on it.
Under Preferred Language, tap Language and select the language you'd like to use.
To change the content language (posts, people, and trends) preferences in your >x< account, follow these steps.
From the navigation menu, tap Settings and privacy.
Tap Accessibility, display, and languages, and choose Languages.
Tap Recommendations and choose from the list of languages.
Choose from any languages listed you'd like to see people, Trends, and Posts in.
Tap Done.