"net.sf.jasperreports.viewer.zoom" no longer exists?

[rcc.gmr]

Hi,

I'm using Jaspersoft® Studio 6.20.6 (CE). 
In my reports, I tried to maximize de width of HTML exports, to fit the iframe container, with no blank left and right margins.
I followed the instructions in: 

But it seems that "net.sf.jasperreports.viewer.zoom" no longer exists in properties name options.
I tried to put manually in Source, the line `<property name="net.sf.jasperreports.viewer.zoom" value="2"/>`. But it appears have no effects.
In my React app, in the iframe, it keeps showing the report too small, not using all available width of the iframe. When I put the Jasper source URL in a browser blank window, the problem is also there. 
Example:

The gray area is free space, not used.

Is it possible to increase the width of the html report?
Why "net.sf.jasperreports.viewer.zoom" no longer exists in properties name options?

Thank you!