How to update MacBook Air

Hi Benidorm1721,

If you're running macOS Mojave or later, you can update your Mac using System Preferences -> Software Update.

If you're running macOS High Sierra or later, you can upgrade to macOS Big Sur by downloading it from the App Store. Be sure to back up your Mac with Time Machine before upgrading.

If you can't install macOS Big Sur, you might be able to upgrade to macOS Mojave or macOS Catalina (again, back up your Mac first): How to get old versions of macOS - Apple Support