I am running ElementaryOS (though I've been experiencing this same issue with other distros) on a Xiaomi Notebook 13 laptop, which I have connected to an external monitor.
The interface size of the external monitor is perfect, everything works fine, but the problem comes with the latop: everythings is extremely small and I can't find anywhere to change it. Particularly, I want to chage the interface scale while keeping the good scale in the external monitor.
I see that some people talk about using the xrandr command, but that makes the laptop screen blurry. In addition, screens overlap and the mouse gets trapped between invisibles areas. Any ideas how I could fix this?