update macOS catalina to big Sur

Source of below and the MBA 2012 Does Not Qualify for Big Sur

MacBook Air

Learn how to identify your MacBook Air.

• MacBook Air (M1, 2020)
• MacBook Air (Retina, 13-inch, 2020)
• MacBook Air (Retina, 13-inch, 2019)
• MacBook Air (Retina, 13-inch, 2018)
• MacBook Air (13-inch, 2017)
• MacBook Air (13-inch, Early 2015)
• MacBook Air (11-inch, Early 2015)
• MacBook Air (13-inch, Early 2014)
• MacBook Air (11-inch, Early 2014)
• MacBook Air (13-inch, Mid 2013)
• MacBook Air (11-inch, Mid 2013)

Hello your mac isn’t supported to upgrade to macOS Big Sur. Please see this support article to view the available macs which can be updated: https://support.apple.com/kb/sp833?locale=en_AU