One of the goals for CK3 was to dumb CK2 down in order to reach a wider audience. I honestly would not describe any of the newer Paradox games as complex (yes, even Stellaris).
CK3 just just looks simpler because its presented in a lot better/cleaner way. (and the fact, that CK2 wasn't as complicated as EU4)
here is some gameplay[1][2] and forum where development happens [3] . There is c# revrite comming ...
[1]https://www.youtube.com/watch?v=lXqBYDSno7w
[2]https://www.youtube.com/watch?v=77mvpSvVu10
[3]http://aurora2.pentarch.org/index.php