Add the shredded rotisserie chicken to a large mixing bowl. Pour in the mayonnaise and ranch dressing. Add garlic powder, black pepper, salt, and lemon juice. Stir everything together until the chicken is evenly coated in the creamy dressing mixture. Let the filling rest for a few minutes so the flavors blend together.

Wash and dry the romaine lettuce thoroughly. Chop the lettuce into small bite-sized pieces. Dice the tomatoes and cucumbers into small cubes and thinly slice the red onion. Keeping the vegetables small helps the wraps roll more easily and gives better texture in every bite.

Warm a large skillet over low heat. Place one tortilla into the skillet and heat for about 10 to 15 seconds per side until soft and flexible. Repeat with the remaining tortillas. Stack the warm tortillas on a plate and cover with a towel to keep them soft.

Lay one tortilla flat on a cutting board or clean surface. Add chopped lettuce in the center, leaving space around the edges. Spoon some of the creamy chicken mixture over the lettuce. Top with diced tomatoes, cucumbers, shredded cheddar cheese, and sliced onions.

Fold the sides of the tortilla inward slightly over the filling. Starting from the bottom edge, roll the tortilla tightly upward while gently pressing the filling inward. Continue rolling until fully sealed. Place the wrap seam-side down.

Use a sharp knife to slice each wrap in half diagonally. Serve immediately or wrap tightly in foil or plastic wrap for meal prep lunches and easy grab-and-go meals.