can we upgrade to New OS Monterey from Mac by clicking on upgrade on software update window? or else its better to go for service centre for better upgrade?

yes, using the software update panel is fine. but you should make a backup before making changes on your mac. this also includes macOS upgrades. i'll also recommend reading this informative, well written user tip: How to upgrade to Monterey - User Tips

Also, in addition to @Yer_Man, always always backup period! You should always be making backups at a very minimum of your important day or better, your system. The built in Apple Time Machine makes this very simple and painless and at the current cost of external drives there is no excuse not to. Trusting all your entire digital life and history to a single device is an accident waiting to happen.

Keep in mind there is no reason to upgrade right away. It is always best to wait at least two months before upgrading to a new OS so that all the release day bugs have time to get sorted out. There are lots of reports at the moment that many USB drives are not working with Monterey and Apple is supposedly aware of the issue according to a couple of reports on these forums.

Plus make sure all your third party software is compatible with Monterey before upgrading macOS. Some software developers may take months before they release an update to their third party app.

If you follow these instructions you should be fine.

How to upgrade to macOS Monterey - Apple Support

There is no "better" upgrade. It's precisely the same software.

Always, always, back up first.