Apple does not only provide updates for the fancy new devices, but also for the older ones with iOS 15. But even very old devices that only run iOS 12, such as the iPhone 5s, still get security updates.
The latest update can be downloaded now. It has the version number 12.5.7 and fixes some security gaps. Those who still use an old iPhone or iPad will at least not be left out in the cold by Apple when it comes to the most important security vulnerabilities.