Maximise window in OS X only using App Store extention We know maximise a window in OS X (like we do in Ubuntu Unity or MS Windows) is not currently possible.

Are there any third party extensions available from OS X App Store to achieve this?

(I don't want to install applications that are not in App store for security reasons.)
Get Divvy - Window Manager app for your specific use case.
It will let you maximize windows in the more traditional sense of taking all the screen space. It's solid, secure, reliable and can do many, many other things in addition to maximizing. There are many others on the store, but if you search this site for Divvy - you'll see it has wide acclaim and utility.
You could do worse than choosing Moom as well.

https://manytricks.com/moom/