I just made the mistake of updating to macOS Sequoia, only to discover that my installed version of Xcode 15 does not open, and there is no path to update to Xcode 16.

This due to the new OS version not supporting old Xcode versions (normal), but also that there is no update currently in the Mac App store to install Xcode 16.

Going to the official Xcode site only links you back to the Mac App Store, with the aforementioned lack of updates.

The net result is there is no Xcode that works on macOS Sequoia barring one of the beta/RCs of Xcode 16