Browser Device Preview Properties And Actual Device Properties Do Not Match

[akheheh]

I seem to be getting a scaling issue when viewing my prototypes on my actual device.
The content rendered on the browser preview is just fine, but when viewing on my actual device, things aren't scaled properly. I'm testing on an iPhone 6s Plus using the iPhone 8 Plus device type.

I outputted the widths of both the line and the screen. On the browser: line is 350, device screen is 414. However, on my actual device, the line is 350 while the screen 276. Can anyone give me an idea how to fix this?

Browser Device Render

Actual Device Render (with output)

Browser Device Output

Code