Basic rice cookers just turn off when the water is evaporated (when the temp goes above ~212˚F). Fuzzy rice cookers are a bit different.
I imagine they’d work fine with just a bit less water and normal settings. You can also wash your rice before cooking (which many people already do for the resulting texture). Or, check the source of your rice. There was a recent study. Texas and Arkansas seemed to have the highest levels. California, India, and Pakistan seemed to have the safest levels. That article also points to old cotton fields as the source, like @anon29537550 mentioned.
