Here you can see three different cooling scenarios under the same conditions. Ambient temperature was stable at 23.3˚C , no overclocking or overvolting was applied. No video output.
RPI 4B no case shows thermal throttling with 3 cores loaded at 82˚C and definitely a demise of frequency ramp with all 4 cores loaded, peaking temperature at 85˚C.
Cooling with CooliPi 4B passively shows top temperature at about 46˚C
Adding a Noctua NF-A6x25 5V PWM fan running at 3.3V shows further decrease of temperatures. Top temperature was around 31˚C.
You can see more on an overclocking page.