Q - " I currently have macOS Catalina 10.15.1 installed on my MacBook Air "
A - The current version of macOS 10.15 is presently version 10.15.7
A - It is suggest updating Catalina to that version.
A - The, there are several Security Update for Catalina
Below link have important information on this topic
Keep your Mac up to date
Thereafter, does this computer Qualify for thank of the newer versions of macOS ?
The Age of this computer will Govern what newer version of macOS it will Qualify to install. Use About this Mac from the Apple Icon on Desktop - the required Information will be there.
With the above information in-hand - follow this How to get old versions of macOS and verify what version this computer Qualifies to install. For Best results use Safari to commence the download as Others may not work.
Safari will open a redirect and open the Apple Store where the download can commence.
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