Downloading WhatsApp IPA for iOS 7.1.2 is possible, but it's not a recommended or straightforward process. If you're stuck on iOS 7.1.2, you may want to consider upgrading to a newer version of iOS to ensure you have access to the latest apps and security updates. However, if you're determined to get WhatsApp on your device, follow the steps outlined above and be cautious of the risks involved.
: Even if a user manages to install a legacy version (like WhatsApp 2.11.8), WhatsApp’s servers typically enforce a "handshake" that rejects outdated clients for security and feature parity reasons. The Ethics of Longevity whatsapp ipa for ios 7.1.2
If you must use an older device for messaging, consider these options, though their support for iOS 7 is also extremely limited: WhatsApp On IOS 7.1.2: What You Need To Know Downloading WhatsApp IPA for iOS 7