A surefire way to ensure that chili is thick is to incorporate lots of dense veggies as you cook like squash, eggplant, carrots, sweet potato, and cauliflower.
You can add the veggies at the beginning, or save them until you notice too much moisture in your stew. Either way, they'll thicken it up and add plenty of nutrients.
This option is great since it doesn’t add flavors or require new ingredients. Just blend a portion of beans and add it to the pot, stirring until it reaches your desired texture.
Simply turn the heat down to low and remove the lid to let it thicken into a rich stew. However, note that it takes a few minutes to thicken up, so plan ahead.
In addition to masa harina or corn meal, cornstarch and flour are excellent ways to thicken chili by making a slurry you can add until it reaches your desired texture.
To make a slurry, mix equal parts of cornstarch or flour and water, until smooth. Add it to the chili and bring it to a rolling boil for a few minutes to activate the slurry.