Turbo will increase the multiplier of one core if the others are not under load.
First of all, do not worry much about heat. The stock cooler may get noisy under load, but no damage will happen.
The cpu will shut down if it reaches dangerous temperatures. That is about 100c.
If you leave voltages on auto, the motherboard will increase the vcore if you raise the multiplier.
You can monitor the vcore now with cpu-z.
Try a stress test now using OCCT. It will shut down the test at 85c.
If you then want, increase the multiplier a step at a time and see how you do.
Monitor the vcore. It should not exceed about 1.3v.
With an average chip, you should not have any problem to the 4.0-4.2 level with the stock cooler. That assumes your case has adequate airflow.
When you are satisfied, implement adaptive voltage and speedstep.
That will reduce the multiplier and vcore when the cpu is no longer under load.