There is no support from dell for fan control on their laptops. It appears that dell does make something for their newer ones called Dell Power Manager, but this still doesn’t let you set fan curves or just manually control fan curves. It just has five options for poorly described curves (they don’t have any info about what temperature they are targeting and when they will ramp up.)
Speedfan works well enough on windows, and there is a driver for i8k on linux so fan control is possible, but there is only three speeds. They are off, 50%, and 100%. The bios is able to smoothly ramp up the fan speed.
On linux you must find a tool that lets you disable bios fan control for it work. Without that the fan will ramp up and then go back to the bios speed. Sleep doesn’t work and function keys brightness takes about 30 seconds to apply unless you renable fan control and then set the fan speed to 0.
All work that has gone into making fan control work was entirely reverse engineered with no help from dell.