Is this your case?
https://www.phanteks.com/Enthoo-Evolv-X.html
It should have come with two 140mm front intake fans and one 140mm rear exhaust fan.
That is excellent airflow.
It allows for a cpu cooler up to 190mm tall; you can install any air cooler made today.
Noctua maintains an extensive list of cooler suitabilities.
Here is the list for the 9600K:
https://ncc.noctua.at/cpus/model/Intel-Core-i5-9600K-389
The NH-D15 will be the strongest of the lot, but others are equally suitable.
You might prefer the NH-D15s which is a high compatibility version that will clear tall ram and is offset to clear graphics cards on some motherboards.
They are about $90.
You can check motherboard compatibility here:
https://ncc.noctua.at/motherboards
I would avoid aio coolers since they are not necessary in your situation.
The NH-D15/s have about the same cooling capability as a 280 aio cooler.
AIO is still air cooling, the difference is where the heat exchange takes place.
With air, you not only cool the cpu, but the airflow also goes over the motherboard vrm's as well as feeding a top graphics card.
Noctua air will be quieter, easier to install, and will never leak.
Did you know that aio coolers do not last forever? In time air permeated the cooling lines and the cooler must be replaced.