Turn the pressure cooker on to the saute setting. Add the meat (add a little oil if using turkey). Cook for a few minutes.
Add the taco seasoning, garlic powder, onion powder, oregano, salt, and pepper. Continue cooking, stirring occasionally, until meat is cooked.
Add the ranch dressing mix if using, Ro-tel tomatoes, green chiles, and chicken broth. Stir, and place a glass lid on the pot to help the broth heat up faster. Once the broth is at a slow simmer, add all of the beans and stir well.
Add the can of diced tomatoes, but don't stir. Place the lid on the pot and lock in place. Turn the steam release knob to the sealing position.
Cancel the saute setting and then press the pressure cook/manual button (or dial) and find the + or - button (or dial) to choose 8 minutes. The pot will take several minutes to build up the pressure before the timer starts.
When the cooking cycle has finished, let the pot sit undisturbed for 15 minutes. Then do a controlled quick release of the pressure by turning the knob toward the venting position in short bursts (I use a wooden spoon handle). When you feel confident that no soup will spew out of the steam, open the knob all the way.
When the pin in the lid drops down, you can open the lid facing away from you. Give the soup a stir, carefully as there could be some steam pockets in there.
Taste and adjust salt, then add the tortillas and the corn. Stir well and let sit for a few minutes, s tirring occasionally to help dissolve some of the tortillas.
Serve with sour cream, cheese, tortilla chips, avocado, red onion, and/or jalapeno.