Need help with an app within an app

Before I go too far down a rabbit hole I was hoping maybe someone here could help or point me in the right direction.

I'm building a kiosk for a client based off a previous kiosk made by another dev. The basics are I have an electron app that runs on large 3 touchscreen TVs next to each other. Within this app runs 3 iframes with a Vue.js app running inside. That all works fine but the Vue apps are all setup to run 1920X1080 and the iframes are rendered inside a small portion of the parent app. How do I have the Vue apps run at 1920x1080 but say at 27 inches and allow the parent app to also be 1920x1080 but say at 55 inches.

Does that makes sense or am I just severely burnt out?