Heat 1 tablespoon of olive oil in a large cast iron skillet over medium-high heat until hot.
Add the sliced red, green, and yellow bell peppers and the sliced yellow onion to the skillet; cook, stirring occasionally, until they begin to soften and develop slight char marks, about 3 minutes.
Stir in the diced cooked chicken, 1 teaspoon chili powder, 1 teaspoon garlic salt, and 1 teaspoon ground cumin; squeeze in the juice of 1 to 2 limes and toss to coat.
Cook just until the chicken is heated through and the spices are fragrant, about 1–2 minutes; remove from heat.
Divide 4 cups of cooked rice among 4 bowls, then top each bowl with the fajita chicken and vegetables.
Add sliced avocado, diced tomato, sour cream, chopped cilantro, shredded cheese, and lime wedges as desired, then serve immediately.