Holding your breath, depends on exertion, and pressure.
I can hold my breath pretty long, sitting on my couch. But. When swimming/diving, that number is usually cut in half.
You can expand your ability to hold your breath, by certain breathing practices.
Pearl divers, do this. They inhale, until their lungs are full. Then, they keep inhaling. The practice stretches your lungs. Increasing capacity of your lungs, increases the amount of time you can hold your breath.
I practiced this method, and got better times. So. I feel that it has validation. But. It takes repeated efforts, and occasionally passing out.