Pseudoscience would be if breathing exercises didn’t have a significant effect on cortisol levels. But some randomised trials have proven that they do. If you apply an additional reason over the top of the breathing like the utterance of certain words that make it work or not, I’d agree with you. From personal experience having attended meditation classes when stressed out, I have found “omm ar humm” very effective in reaching a relaxed lower stress state. I didn’t know this was called box breathing to make the omm (in) arr (the pause held at the heart) and the humm (the outbreath) the same length. So that was a lesson for me. I have however experimented with different non religious words and found it effective in reaching that pleasant meditation very rapidly.