Nope, that will give your unit 500 range. Changing aquire range via triggers will not change the unit range at all. It should however mean you will start to attack at different times.
If you give a unit with 2000 range an aquire range of 500 via triggers (as it will need a base of atleast 2000 inorder to have that range), I imagine it can shoot 2000 range but will not automatically aquire a unit until it reaches 500 range (ordering it should still give access to all 2000 range).