macbook air Operating System
How to change the MacOS on MacBookAir
MacBook Air 11″, macOS 10.15
MacBook Air upgrade:
The model year of a MacBook Air is available at Apple menu > About This Mac.
A mid 2012 MacBook Air can be upgraded to Catalina 10.15.7 but no later
A mid 2013 and early 2014 MacBook Air can be upgraded to the latest version of Big Sur macOS 11 but no later.
An early 2015 and 2017 MacBook Air can be upgraded to the latest version of Monterey macOS 12 but no later.
A 2018 and 2019 MacBook Air can be upgraded to the current version of Sonoma macOS 14 but no later.
For all of the above, see instructions in: How to download and install macOS - Apple Support
A 2020 or later MacBook Pro can be upgraded to the current version of Sequoia macOS 15. See: How to upgrade to macOS Sequoia - Apple Support