There are a few different ways that you can thicken up white chili. One of the easiest ways is to mix some cornstarch or flour into the soup. These thickening agents will make the chili thicker before you serve it. You can also try mashing some white beans and then adding them to the chili, which will allow the soup to thicken. The toppings that you use can also make a difference in how thick the chili ends up. Try adding some vegan cheese, tortilla chips, or croutons to your chili if you prefer extra thickness.