On your iPhone, go to Settings > General > About and look at Model Name. If your phone isn't on the compatibility list, it will keep receiving iOS 18 security patches for a while, but you won't see any of iOS 26's new features.

Apple today released iOS 26.2, the second major update to the iOS 26 operating system that came out in September, iOS 26.2 comes a little over a month after iOS 26.1 launched. ‌iOS 26‌.2 is compatible with the ‌iPhone‌ 11 series and later,