Download and install
HWInfo64. It's free.
Once installed, look for a Sensor readout called CPU Die (average). There's also CPU (Tctl/Tdie). Tctl/Tdie will be pulsing up and ramping down as the processor boosts, it's the instantaneous readout of the highest sensor at the moment. CPU die (average) is a moving average of the sensor readings that gives a very good idea of the CPU's true thermal state.
What is the (average) reading? since it always shows the true thermal state of the CPU that's what you want to try and keep low when the processor is at low useage. If it's high (65-70C or higher) with nothing open then you either have a cooling problem or there's a process working the CPU hard that you don't know anything about. There are some utilities that do that: Corsair's Link or iCue (whatever) is famous for it.
Also, how high are the Tctl/Tdie pulsed readings going?
You can also use Ryzenmaster to get the average readings, but it doesn't give the instantaneous readings. Unfortunately, all BIOS's seem to use an instantaneous sensor reading to control fans so that's why they pulse if you don't set a good fan control curve. Don't let the fans get to an annoying speed before about 80C. Tjmax for Ryzen CPU's is 95C so never 100% before 90 or 95C.
And lastly, another thing you can do is instead of following CPU temperature to control the fans, follow VRM temperature as it directly follows CPU load. But it's also a bit slow to respond so you have to raise fan speed a bit early in the rise, especially a CPU fan. But at least there will be no pulsing.