Unable to use WhatsApp on my iPhone 6 due to older iOS version

Meta WhatsApp app requires iPhone 6S, iPhone 7, or newer.

iPhone 6, iPhone 6 Plus, and earlier iPhone models, are not supported.

You can provide your app support feedback to Meta WhatsApp support.

If that iPhone 6 contains data you value, I’d keep a current backup of it. Particularly given the apparent display damage. That sort of damage only tends to progress.

Means just what it says. You need a newer phone that will support a version of iOS higher than 12.5.7.

WhatsApp has decided to no longer support older iPhones.

In effect, WhatsApp is forcing you to buy a new phone.

Do you have a question? The message is pretty clear.