I don't see any software issues. I do see Webkit had some high CPU usage. Webkit is part of Safari (and may be possibly be used for the web portion of other Apple apps).
When you performed the clean install of macOS, did you erase the whole physical drive or just the APFS volume/Container? If you didn't erase the whole physical SSD, then try running Disk Utility First Aid on the hidden Container. Within Disk Utility click "View" and select "Show All Devices" so that the hidden Container appears on the left pane of Disk Utility. Even if First Aid says everything is "Ok", click "Show Details" and scroll back through the report to see if any unfixed errors are listed. If there are any unfixed errors listed, then run First Aid from Internet Recovery Mode (Command + Option + R), otherwise you will need to erase the whole physical SSD before restoring from a backup or clone.
This is a longshot, but run DriveDx to check the health of the SSD. Unfortunately the Apple SSD's don't contain much information in their health report, but it never hurts to check. Post the complete text report here using the "Additional Text" icon which looks like a piece of paper.
Since you don't have any software installed which would cause the problem this means either your laptop has a hardware issue that will need repaired, or a connected external device is causing the problem (assuming it is not a file system issue). If the problem occurs with no external devices connected, then it will be a hardware issue with the laptop.