Zoom an iframe to to scale instead of being responsive?

Anyone have any idea on how I might be able to set a ‘zoom’ on an iframe ?

My goal is to have a split screen simulated website builder. I currently have a floating group on the left with the prompts to guide users to make changes or type copy for each section of their website, however I want to be able to show the effect on their website.

When I set an iframe the content is automatically responsive. I would rather it just zoom out to show a desktop version of the page instead of a responsive version. Anyone have any ideas?

My only guess is that I could build a scaled down version of the page as just a way to simulate what it looks like.

Split Screen with responsive sizing:

I want this to appear desktop layout, but just zoomed out.

Non-responsive version