I run my 9900K with a 190w power limit, 240mm AIO. I get about 80c when running Prime95 (-3AVX) and am happy with that setup.
If I must use the L12 or lesser cooler, I’ll probably lock it at less than 150w.
I've mounted 8x i9 9900K in the last 2 months.
Power consumption, hence heat, depends on the motherboard, CPU, bios, settings and can lead to significant difference IMO.
The ideal speed IMO is the stock Intel turbo clock speed without any limitation coming from power consumption. I can get 2050/2070 in Cinebench R15.
On this CPU I get the most heat from Cinebench R15 / R20. So I run Prime95 with settings that match such power consumption and heat. I don't use AVX aware Prime95 as that can be under clocked. I use Ver 266 with settings such as 96 / 144.
One of those i9 9900K runs on Asus Strix Z370M with a Cryorig H5. This system gives very good results. All core running @4.7Ghz consume circa 150W/155W. With these settings after half an hour you have circa 90° temp inside a MasterBox Q300L.
Another of those i9 9900K runs on Asus Prime Z370-A II with a Noctua NH-D15S. This system gives good results too. All core running @4.7Ghz consume circa 150W / 155W. With these settings after half an hour you have circa 83° temp inside a NZXT H500.
Another of these i9 9900K runs on the same Asus Prime Z370-A II (but it's less "lucky") with a Cryorig H5. Even though the motherboard and CPU and bios ver are the same, this system finds stability when all core are running @4.7Ghz @ circa 160W / 165W. With these settings after half an hour you have circa 94° temp inside a Phanteks P300 Glass.
What I'm trying to say is an i9 9900K can run at full turbo Intel clock settings consuming 150W / 170W.
This means All Core @ real 4.7Ghz which is the hotter scenario as the loaded core decrease temp decreases.
Hope it's helpful and meaningful.