Unsure which version of iOS your iPhone can run ... With the end of support for iOS 15 (last updated in July 2024), the iPhones 7, 6S, 6S Plus and 1st gen SE has also ended.
iOS 15 will run on the iPhone 7, iPhone 7 Plus, and all newer iPhones that have been released, making it compatible with devices that have an A10 chip or newer.