There are many ways to thicken chili. The simplest is to mash some of the beans (if they are in the chili) or let the liquid evaporate.
Wheat flour, white flour - It is easier to mix the flour with a little water before putting it into the chili pot.
Masa harina – highly processed; so is yellow cornmeal. Not too good though it has a long shelf life.
Breadstuffs - stale or fresh bread, crumbled up, can be used to thicken chili. Corn bread, biscuits, and cracker crumbs also work. Add near the end of cooking.
White stone ground cornmeal is good.
Other thickeners - ground seeds and nuts do well as American Indians knew. Even peanut butter works.