Over and above the usual way to determine the Mac's software levels : -
> About This Mac
and Software Update : -
we also have the command line: -
sw_vers
ProductName:Mac OS X
ProductVersion:10.15.7
BuildVersion:19H15
ProductVersion:10.15.7
BuildVersion:19H15
and: -
softwareupdate -l
Software Update Tool
Finding available software
No new software available.
Finding available software
No new software available.
Getting ready for Big Sur, in case you couldn't tell 😂