Is it possible to change CC's resolution? I tried using settings.ini but that didn't have any effect.

In order to change the resolution, you'll have to modify the menu and Scene backgrounds. Plus, CC wasn't meant to work at a higher resolution yet. Think of it as a fog of war.

There is/was a general mod for B18 or B19 to use CC at 1024x768, which works pretty well. If you can find it, you can use that as a base guide for what you should modify. I strongly don't recommend playing at higher resolutions than that; I play for a while at 1600x1200 and it made the game far too easy and lagged at times.