The short answer is that I haven’t and do not really know what level of improvement you may achieve. That said it sounds like the 13900k is a good CPU.
-
Does your motherboard definitely support the 13900k? And if it does are there any aspect about it that may hinder the full potential of the processor?
-
Before you go to any additional expense have you tried lowering just a few settings slightly to gain a smoother experience. There’s a good video somewhere that compares loads of the various setting for visual comparison. I would suggest that would be a good place to start rather than throwing money at it. You already have a pretty good machine, if it were me I would aim to make it work for me and consider a more comprehensive upgrade in the future when 13900k and 4000 series Nvidia cards have been surpassed.