If there is a 4K monitor but the video card does not pull, can I use it as FullHD?

Question

Monitors

I've found several ways to run 4K, but I'm not sure how it will work. And I would not like to engage in an exchange and so on.
Actually, the question is: will I be able to use FullHD or, for example, 2.5K or will there be dregs?
In the sense that at 1920 you can use 1024, but on a poppy, on Windows, the image is distorted and it turns out to be dregs. Won't this happen on a 4k monitor when using 1920?

Answer 1

If the resolution is set exactly two times less than the native one, there will be no turbidity.
In the case when you have 1024 instead of 1920, you get haziness, because for one pixel of the image there are not one or two monitor pixels, but 1.875 pixels, i.e. approximately every second pixel shows a mixture of the color of two adjacent ones.