You'll see an iOS 18.7 update, but that's not the one you want to select. Instead, just below that tap on Upgrade to iOS 26 ...

Apple has finally released macOS Tahoe, and it's a free upgrade for all supported Macs. Here's how to know whether you qualify and how to upgrade to macOS Tahoe!

Apple has released new features and capabilities across each of its software platforms — iOS, iPadOS, macOS, watchOS, tvOS, ...