Grid Axes.

Is it possible to have fixed View Grid ? When I zoom in, grid becom more shallow.
But in 3D view everything is ok.

View / Auto Scene Scale should be off.  When on, it dynamically changes the grid size.

Changing the "Auto scene scale" to off, will not change how the ortho view floor grid changes.

There is an option:- View > Display > Display Grid Size" that shows the current grid size when it changes (it shows top right of viewport)

If you really need to stop that. What I do (when needed), is to disable the floor grid, and use the workplane (unlocked).