When you are using a different screen resolution (e.g. 1440p or 4k), you can't copy the sens settings of someone using a 1080p screen. Well you can, but it will feel different. If you want to copy it, devide it by their resolution and multiply it with yours. Example:

0,3 / 1080 x 1440 = 0,4

So a 0,3 sensitivity on 1080p will feel the same as 1440p on 0,4. Keep in mind that this only applies if you are using the same dpi settings on your mouse as well.