Thank you.  This (Dell Power Manager Service) worked perfectly on my refurbished 7490 Notebook.  Now the CPU goes up to the full 3.6MHz frequency sporadically as needed and back down to below 1Mhz as desired, and also now the CPU max. temp goes to only 82 degrees centigrade vs. 99 degrees before installing the Dell Power Manager Service as you suggested.  For some reason however, the proper downloaded exe from the support page for my model would not install (could not create path/folder) so I had to extract the files to a folder and then run the exe from that folder. I viewed a video of Dell employee stating that running a top TDP temperature briefly is now how they design systems and it's OK, however I prefer a max. TDP in the 80 degree range, so thank you!
I own a Dell Latitude 7490 i5-8350U and find it runs very hot, even when it's just doing basic things like browsing the web. Reading a number of forums this appears to be a common problem with the 7490.  So far I've changed the CPU paste, updated to the latest bios and now running Windows 11 but still have the same problem. I really like this laptop so would like to get the overheating problem sorted - is there anything else I can try? Thanks   
Latitude 7490 Overheating