Brandon, the simplest way is to move to the current version (v2019.2.?).

You can have full width (single object on a row) and/or full width background (row formats), and you can define multiple breakpoints if you wish (pro).

In v12 you could emulate full screen down to mobile by simply adding resolutions, but back the there were many limitations (from memory 964px was the greatest allocatable width).

Since your existing project/s is/are in v12 pro you must upgrade to the pro version (check out your profile (top right, this page), and click on offers). If you choose to upgrade to evolution you will need to manually recreate any existing projects.

Personally - I would not use 3rd party code, it is just too easy in the latest versions.

"please give me script for full width pag" - Hello.You need a little knowledge of the CSS.

Is it only for one object - or all, that you want full width?

...!...

1) - content, (text, object, etc.) ...?...

2) - or full width/height responsive background image (*) ...?...

... ... 

(*) - in this case you post the link of your page, so that I can verify my ideas ...

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... warning! ... expired! >>  https://helpcenter.websitex5.com/ru/post/196325

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Hi Brandon, 

as Esahc suggested, you should consider purchasing the latest WebSite X5 2019.2, which does include this feature and which you can try here: https://www.websitex5.com/download/v2019.2/wsx5_pro_demo.exe

Please let me know if you have any questions. Kind regards.