You have apparently tried to "linuxfy" your macOS by adding apt through a package manager. It is not going to know anything about Apple's software update process when it is designed to work with Debian Linux package repositories. Those are not designed to be installed on macOS which is not based on any Linux distribution.
If an application is installed from the Mac App Store, then that application will inform you that you have updates when those applications are updated. If you install an application from outside of the Mac App Store, that application may or may not have a check for Updates menu item under its application or Help menu. In some cases, these applications can pop a dialog informing that there is an update available to install.
If the application is installed through the homebrew (brew) package manager, then you won't know there is an update for it until you run brew update and it tells you that you have nn outdated packages which will be updated when you run brew upgrade.
The two principal package managers for macOS are homebrew (what I use) and MacPorts. Both require that you have either the current Xcode for your platform installed or the respective command-line tools for Xcode.