The Apple Diagnostics @John Galt suggests running are usually pretty good at identifying issues with the Mac's cooling system, so if no issues are reported with the cooling system, then I would suspect a software issue. Software issues are much more likely to cause a computer to run hot.
To look for possible software issues, run EtreCheck and post the report here so we can examine it for clues.
The Apple USB-C Intel laptops do run very hot so that is not unusual in itself. Even just launching an app will cause the CPU temperature to spike to 60C or even 80C. It is not unusual for these Intel Macs to be running at 60C - 90C for most tasks. Under very heavy loads the laptop may run close to 100C with the fan(s) running at high speed. This is all "normal" since the CPU will become throttled if the laptop's cooling system is unable to keep the CPU temps below about 100C.
If the fan(s) are running at higher speeds, then you definitely do not want to touch the heatsink as it can easily burn you. After all 100C (212F) is the boiling point of water. Even 60C (140F) can cause a burn and the USB-C Apple laptops tend to run at 60C most of the time except when idling.
If we don't see any clues in the EtreCheck report, then you can try testing a clean install of macOS (no third party apps and no restore from a backup). If a clean install still has the laptop running too hot, then it likely indicates some sort of hardware issue with the Logic Board. Make sure to also disconnect all external devices in case one of them is causing a problem.