From your second screenshot, it seems like your current iOS version (you didn't reply to my question) is prehistoric, earlier than 12 (minimum required by Whatsapp app), and you'll encounter many difficulties trying to update your iOS wirelessly (via wifi).
Should be this case, I suggest that you update your iPhone via computer (if you don't have a computer borrow one from your friends/neighbors, or ask for help at an Apple Store or Authorized Service Provider), then learn how to update your device manually if you're using a Mac with macOS Catalina or later, or if you're using a Mac with macOS Mojave or earlier or a Windows PC.
If you still get no help, contact Apple Support directly, using this link:--> Get Support
Regards
Giulio