If you can install a modern lightweight browser like Opera Mini or a newer Android System WebView , you might be able to use WhatsApp Web, though this usually requires a "parent" phone to be active.
If Meta finally pulls the plug on legacy versions, consider these alternatives for your Android 4.1.2 device:
If you are still using a device like a or Sony Xperia Z , you have a limited window to save your information. About supported operating systems | WhatsApp Help Center
: Do not waste time hunting for a magical APK. Instead: