If it can't function on a desk by design then it really has no right of being sold for use. The feet should keep it up and that should be all it needs to deal with air flow :)
Normally you can check CPU temperature in the BIOS, in a manufacturer application that shows it if they offer one, or in 3rd party applications such as HWMonitor https://www.cpuid.com/softwares/hwmonitor.html or maybe SpeedFan https://www.almico.com/speedfan.php
The thing is a computer - even a laptop - should be able to max out and continually run at 100% CPU with no issue. If it can't then either its designed really badly and shouldn't have been sold or it has a physical problem like dust, driver, firmware issue, or factory flaw that got past QA on that specific unit or batch, etc.
The dirt cheap and 8 years old now laptop I have runs at 100% as long as it needs with no problem. That is how it should work.