If you have never downloaded WhatsApp on that Apple ID, this option won't appear. You can fix this by briefly logging into your Apple ID on a newer iPhone, "buying" (downloading) WhatsApp there, and then returning to your old device. Method 2: Using iTunes 12.6.5 (PC or Mac)
If you are determined to try, the following methods are often discussed in community forums, though their success rate is extremely low in 2026: About supported operating systems | WhatsApp Help Center whatsapp old version for ios 9.3.6 download
If you require WhatsApp for communication, you must upgrade your device. An iPhone 4S (stuck on iOS 9.3.6) is effectively obsolete for modern encrypted messaging. If you have never downloaded WhatsApp on that
Do not download "IPA files" from random websites. Those are often malware. Use Apple’s official legacy download system. An iPhone 4S (stuck on iOS 9