In a large skillet, heat olive oil over medium heat. Add the diced chicken, chili powder, cumin, garlic powder, salt, and pepper. Cook until the chicken is browned and cooked through, about 7-10 minutes. Remove from heat and set aside.
In the same skillet, add the corn and cook for 3-4 minutes until heated through and slightly charred. Remove from heat.
In a small bowl, mix together the mayonnaise, lime juice, cayenne pepper (if using), and half of the cotija cheese. Stir until well combined.
To assemble the bowls, divide the cooked rice among four bowls. Top each bowl with the cooked chicken, charred corn, and the mayo mixture.
Sprinkle the remaining cotija cheese and chopped cilantro over the top. Garnish with sliced radishes and serve with lime wedges on the side.