Hi, is there any way to resize the game window? Want to play at a lower res then my desktop res but wanna enlarge the game window to ocupy most of the screen

You can set arbitrary resolutions with the highres-patch.
I never found a way to force a windowed mode, but if you are on mac or linux, you can emulate a virtual desktop in wine, thereby running the game in a window with a chosen resolution and size, and with window decorations.

On windows 10, you could install wine via WSL, which would be the weirdest workaround ever.

From the Hi-Res Patch notes:

COMPATIBILITY

Game version:

Arcanum.exe version 1.0.7.4 (English) required. Any modifications of it (this includes the UAP) will also work. Only Arcanum.exe matters, the patch doesn't modify any of your other files.

Resolution:

Any resolution is possible, if it isn't smaller than the original 800x600. Even non-standard resolutions like, e.g. 1333x789 will work, if the game is run in a window or your video card supports custom resolutions.

Note: If you have the UAP installed you can run the game in a window by using the '-window' command line argument. Otherwise, you will have to use D3DWindower or similar software.

Im already playing in windowed; my desktop res is 1680x1050 and i run the game in window of res 1440x900. What i want is to set the game window to fit almost all the screen while it remains at 1440x900. I guess a solution would be to set my desktop res to 1440x900 but dont want to do that.

ps im on w7