Can't Install Catalina

https://itunes.apple.com/us/app/macos-catalina/id1466841314?mt=12&l=en-us

Alternatively if you are determined to see it in System Preferences—

running Mojave 10.14.6.—trying to download Catalina, it is not showing up as a system update

From the Applications/Utilities/Terminal.app copy and paste:

sudo softwareupdate --reset-ignored

(please note your psswd will not echo on screen—type it in anyway to proceed)

relaunch System Preferences>Software update

1. Going from Mojave to Catalina is not an, "update," it's an, "upgrade. "10.14.6" was the last "update for Mojave.
2. Download Catalina form the App Store app.