First check if your MacBook Air is compatible with macOS 27 Golden Gate. That will depend on the specific model. There is no "MacBook Air 2" in Apple's catalog. Do you mean M2? If so, that is compatible with Golden Gate.
Apple’s current compatibility list includes MacBook Air with Apple silicon from 2020 onward:
macOS 27 Golden Gate is compatible with these computers - Apple Support
If macOS 27.0.1 does not appear in Software Update, try the following steps in order.
- If you are using a VPN, shut it off.
- Restart your Mac.
- Go to System Settings > General > Software Update and check again. Press Command-R to refresh that settings pane, just in case.
If macOS 27 still does not appear, you can check which software updates are currently being offered to your Mac.
Open Terminal (find the app with Spotlight or in Applications > Utilities) and paste the following, then press return:
softwareupdate --list-full-installers
If macOS 27.0.1 appears in that list, you can download the full installer with:
softwareupdate --fetch-full-installer --full-installer-version 27.0.1