Well, this is loaded question as I’m in Texas and they take chili very seriously here.
But to answer your question, the basics of chili are ground BEEF, spices (suited to your taste and heat tolerance), kidney beans, onion, diced tomatoes and tomato sauce.
I top mine with cool diced white onions and sharp cheddar cheese and I serve it with cornbread on the side (though Saltines work in a pinch)
I hope that starts to answer your question. Chili recipes could dominate a thread of their own, you know?
I thought for the Texas cook offs, there are no fillers, meaning no beans. I’m talking about the big boys, where first prize is 10K or more.
I put green olives in mine. They used to do a skillet chili in a Miami restaurant I frequented and I stole their idea. I also do the cheese on top.