Yes, you can connect the RGB fans the the motherboards RGB header and create a fan curve (in some BIOSes or temperature and rpm thresholds in other BIOSes). This way, the fan RPM will still adjust RPM according to temperature readings (as long as you can set the temperature reference to CPU temp instead of case temp)
Otherwise, there might be some software for the motherboard or maybe some 3rd party software that can work in a similar way to the NZXT Cam software, and adjust both your fans' RPM and RGB settings according to CPU temp, but I personally don't use software of that type, so I can't recommend anything specific. It has also been a very long time since I used a fan controller, so I'm not very familiar with the options available, but I'm sure someone else can recommend something.
But from my own testing, the stock fans and NZXT Cam software provides the best solution when it comes to the Kraken x62 - and I say that, eventhough I'm not particularly impressed by the Cam software, and I previously have always put Noctua Industrial fans on the AiO's I've owned, but they do not work with the Kraken x62 due to various differences in the fan design (minimum RPM settings among other things). I wasn't aware of that until I tried swapping the fans just a few weeks ago, but from internet forums I can tell this has been an issue for years with NZXT AiOs.
But I really wanted to use those Noctua fans, which is why I tried multiple solutions trying to run the fans off the motherboard headers instead - and I still came to the conclusion, that this particular AiO works best with stock setup.
But I really hope you can maybe find someone who had better luck setting the Kraken x62 up with RGB fans. But I suspect, from my own experience, that you will have to fiddle with it for a while, until you find the best setup - with different fans, it's not really a plug 'n play thing.