In the HTML of the web page add the meta tag with the minimum scale set to 0
From the client side, we can shrink the web page using the initial scale method.
config.setProperty(BrowserFieldConfig.INITIAL_SCALE, new Float(value));
In my case, this meta tag was not there and so the initial scale option was not working after a certain limit. By this being set in the html, we can scale it to any value between the minimum/maximum defined scales.
With this, my problem was solved.
But, if you want to fit it to the device screen, you'll have to calculate the scale value to make it set to the screen size in all the devices irrespective of the resolutions.