Pamac updates while installing a application

whenever I tried to install a application whole system upgrade starts, is there a way to install only the application I want and upgrade system other than while installing application

You can’t.

Installing a package requires a dependency check, and for that you need to have the latest version of those dependencies. The safest way to achieve that is to enforce a system update beforehand.

You can but it is not recommended - as it may create a partially sync’ed system - which is unsupported.

You can turn this off. Go to Pamac Software center → Preferences → Advanced and enable the checkbox “Do not check for update when installing…”