What exactly is "Clear Motion Index 120Hz CMI" does it give you what the call the soap opera effect?
Not really. It's simply some marketing term for an enhanced refresh rate for the display, likely done in software and not the native screen refresh rate. Soap Opera Effect generally comes from frame smoothing and judder controls. Each TV brand likely labels it differently.
Ohh! A guess they use that to trick people into buying the product under the assumption that it's 120Hz. So I guess I won't be getting that soap opera effect that I like so much since I got the 43 inch 4 series?
Oh, you can get the SOE on any size of TV. It certainly becomes more noticeable on larger screens, but those settings will do it on any size. Look for settings such as "smooth motion", or some such terms. I usually just disable them all. Some TVs allow customizing the setting, and often you can turn just the judder control up a notch and leave the smoothing off, so SOE doesn't become noticeable.