There's a wide variety of different breathing techniques that can be used for specific purposes. It's been literally life-changing for me. Some techniques can help you getting out of a bad moment (anxiety, stress,...) but others have much deeper effects and can transform how you function as a human being.
You can for example check the following broad categories: a) Conscious breathing (Holotropic, rebirth, and the likes), b) Pranayama (Kapalabhati, anuma viloma,..), c) Buteyko + McKeown, d) Anapana Sati, e) Qi gong, f) Wim Hof.
It takes time to absorb the practical knowledge and use it in daily life but as the question asked, I was richly rewarded for the time I've invested in mastering these techniques.