How to use pacman(Command of pacman) to install "Add or Remove software Or Pamac

Not in an obvious way. pamac is not in the repos. You need to use yay or another AUR helper to build it from AUR.

You could install a 3rd party repo and then use pacman to install but that carries risks.

Likewise, you would build the package with makepkg and then install it using pacman. Since that is that same thing that yay does for you this doesn’t add a lot of value.