ios update

Unfortunately, if your app requires a newer iOS than 15, you’ll need newer hardware.

Your “7” can’t be updated to iOS 16 (or 17).

iOS 16 and iPadOS 16 are compatible with these devices - Apple Support

You will need to contact WhatsApp for help with their software, this is not an Apple product.

Here is a link to their help page.

https://www.whatsapp.com/contact/?subject=messenger