The fastest way to enlarge your cursor is to go to www.kde-look.org
and look in the X11 Mouse Themes section. There are a ton of cursor themes there. You need to download them, install, select the one you want to use, and restart KDE. If you installed it correctly, it should show up.
The other way is to look at your package manager for cursor themes. Most distros include several. Install them, and change the theme you are using.