How can I update my Safari on macOS Catalina 10.15.7?

I'm currently running macOS Catalina version 10.15.7 and am trying to update to the latest version of Safari. I've followed the procedure suggested online (Apple menu to System Preferences to Software Update) but no option for updating my web browser shows. How can I update from version 15.6.1 to the latest version ( 18.3 )?

[Re-Titled by Moderator]