If you want to put the standard scope of CS 1.6, you can do it. How? Read on:
But if You don't like it, then you can change it to this:
- Enter CS:GO
- Start playing on any map
- Press the button "Esc"
- Choose "Help and settings"
- Select "game Settings"
- In paragraph Style sight" choose "Classic"
- Click "Back" and "Resume game"

You can add a small dot in the center of the sight, to do this, write in the console the following command:
cl_crosshairdot 1

To increase the size of the sight, enter the following command:
cl_crosshairsize 7 or cl_crosshairsize 10 (can be any)

To increase the thickness of sight, enter the following command:
cl_crosshairthickness 1 (this variable is also changed to different values)

And that's all. Now the sight was the same as it was in cs 1.6.

Well, for the most curious and lovers of experiments, and those who like longer to set up CS or not satisfied with the standard sight of 1.6 here advanced settings sight and their description:

And so each team separately.

cl_crosshairstyle

Sets the appearance of the target:

cl_crosshairstyle "0" = Standard from CS:GO, dynamic (expands when shooting).
cl_crosshairstyle "1" = Standard from CS:GO, statistical (not expanded when shooting).
cl_crosshairstyle "2" = Classic from CS:1.6, Dynamo-statistical (not greatly expanded when shooting).
cl_crosshairstyle "3" = Classic from CS:1.6, dynamic (expanding when shooting).
cl_crosshairstyle "4" = Classic from CS:1.6, statistical (not expanded when shooting).

cl_crosshairsize

Command cl_crosshairsize, You can set the altitude of sight (see screenshot above). The higher the value, the greater the height of the sight.

cl_crosshairthickness

Command cl_crosshairthickness, You can set the width of the sight (see screenshot above). The higher the value, the greater the width of the sight.

cl_fixedcrosshairgap

Only possible with a bunch of commands cl_crosshairstyle "0" and "1".

With the team cl_fixedcrosshairgap, you can change the distance between the beams (strips) of Your sight, You can narrow the distance and to expand. The default value of this command cl_fixedcrosshairgap "3", the smaller You set the value, the closer is the distance of the beams.

cl_crosshaircolor

Only possible with a bunch of commands cl_crosshairstyle "2" and "4".

With this command You can set the color of the crosshair.

For this command the following values:

0 = Red.
1 = Green (standard).
2 = Yellow.
3 = Blue.
4 = Blue.
5 = Allows you to add your color.

When setting value is "5", You becomes available for another 3 values of the colors in the colors RGB. Selectable from 0 - weak tone colors, up to "255" strong tone colors.

cl_crosshaircolor_r

This command sets the red color.

cl_crosshaircolor_g

This command sets the green color.

cl_crosshaircolor_b

This command sets the blue color.

Each of these three teams can reach from "0" to "255", the higher the value the brighter the color.