If your iOS device is running iOS 9.3.5, you may not be able to download WhatsApp from the App Store, as the app may not be compatible with your device's operating system. In this case, downloading WhatsApp IPA for iOS 9.3.5 is a viable alternative.
No – WhatsApp Web also requires a connected phone running a supported version. whatsapp ipa for ios 9.3.5 download
This only works if the app is tied to your purchase history. For users who reset their device or created a new Apple ID, this option is gone. If your iOS device is running iOS 9
Meta announces server shutdowns for legacy versions months in advance. Once they deprecate the API, you will see a message: "Please update to the latest version of WhatsApp to continue using this app." At that point, there is no fix. This only works if the app is tied to your purchase history