how to turn off optimization in games?

For example, arma 3. With reshade installed, shadows and grass start to load up only in range of 10-15 meters.  Obviously, its because of reshade, but in the programe there is no such option. How can I return my far shadows and grass? Im not even sure that if I uninstall reshade I'll have it back.

It is literally impossible for reshade to make grass pop in and out closer/further. All reshade can do is add a filter onto the screen. You would need a game-specific program to make grass cull differently.