How to fix browser size in pixels?

Question

macOS

With the purchase of a new iMac Retina 27'', there was a problem with the layout of sites and web surfing.
Rubber sites are stretched to full resolution, while the average resolution of an ordinary user is 1920x1080. Is it possible to fix the size and aspect ratio of the browser window on Mac OS or using a plugin for Firefox? (Not content with developer tools, namely the size of the window itself)

Answer 1

Try it with AppleScript. Recipe here - https://www.labnol.org/software/resize-mac-windows...
Or like this (also via AS) - https://alvinalexander.com/source-code/mac-os-x/ho ...

tell application "Safari"
activate
set the bounds of the first window to {140, 0, 1160, 775}
end tell