Hi!
Here is what you can do to keep mouse cursor in desired position:
First create GUI texture (or add GUI texture component to empty game object) and set scale to 0, 0, 1
For texture use your desired cursor GUI texture then set your texture dimensions as you want, for example use 50 for x and y, add offset - 25 to x and y so it can be centered (you can divide your screen and set desired values as well). After that use actions that are provided on this image, get mouse x, get mouse y and store those float values, then use float clamp and clamp those values as you want every frame so for next step is to set position for that object in world space every frame (for x value use your stored value from mouse x and for y use stored mouse y). Last thing you want to do is to hide mouse cursor by using set mouse cursor action and check hide.
And that's it, you got your cursor on screen positioned on screen!
Cheers!