This game don't allow widescreen resolution setting in option menu.
I investigated whether or not in other way.

#1 change configuration

This game has no configurable file.All settings without key binding are stored in registry key.
Resolution setting is stored below one.
HKEY_LOCAL_MACHINE\SOFTWARE(\Wow6432Node)\Pivotal Games\Conflict Desert Storm\Device Settings

hexadecimal/(decimal)=resolution,color bit

01(01)=640x480,16bit
04(04)=800x600,16bit
05(05)=1024x768,16bit
06(06)=1152x864,16bit
0a(10)=1280x960,16bit
0f(15)=1400x1050,16bit
14(20)=1600x1200,16bit
19(25)=640x480,32bit
1c(28)=800x600,32bit
1d(29)=1024x768,32bit
1e(30)=1152x864,32bit
23(35)=1280x960,32bit
27(39)=1400x1050,32bit
2c(44)=1600x1200,32bit

Any other number are set to 800x600,32bit.
You can't get widescreen with this way.

#2 debug mode

There is other way that change game program into GOD and DEBUG mode by replacing specific hex.

1.Open DesertStorm.exe with hex editor.
2.Search "2d66202d6400"
3.Overwrite it by "2d662d642d6d".!Don't change number and position of hex.!

If you modified correctly then icon is same one,If you missed then icon will change to blank.

http://www.absolutcheats.com/pc/conflict-desert-storm-cheats
GOG version is not compressed version.

After modified it,run game and enter 3d graphics part.
1.Toggle Debug Mappings Activation - [Left Shift]+SLASH/QMARK
2.Toggle Widescreen - [Left Ctrl]+N
then,black bar appear top and bottom that shrink your vertical view,they call it "widescreen".