The thermostat is just a "valve" that redirects and/or blocks coolant flow -- it is NOT linked to any accessories.
I think these things (aux. fan, etc.) that you asked about are controlled by some electrical sensors -- they open or close a circuit (sometimes "grounding" a circuit) at some preset temperature, in turn activating a relay that energizes the fan, etc. You might look into substituting a different sensor that is preset to a lower temperature.