Yes, you can adjust intensity with the Prime. It's easier to do from a computer than mobile, but can still be done. You can set the overall light spectrum (10k, 12k, 20k, etc) and intensity (percentage). Right now you are in the custom spectrum mode, where you adjust the intensities of the individual colors. To toggle to the overall color spectrum mode, in your screenshot above, click on the circle thing to the left of the "Done" button. The outer circle is the spectrum and the inner circle is the intensity.