oh u came to the right place i am the master at this! i used to be soooo skeptical of breathing techniques, til one day to my shock it actually worked the trick isnt just getting oxygen, its opening ur mouth/diaphram wide enough where you yawn (which medically resets the nervous system slightly and does WONDERS, my dog even knew to naturally do it!), and you want to expand ur lungs as much as u can (opens diaphram) so take a huge deep breath til ur lungs feel full, then stuff a little more
air in there. and keep doing that. then u need to breath slowly and purposefully. focus rlly hard on the feeling in ur lungs and the control needed to smoothing breath in, feeling them expand, hold it a second, then slowly breathe out, and notice ur chest sink i promise its like magic when you get the controlled smoothness right
the other thing that changed my life is dancing regularly, it loosened me up and got out the extra energy i was holding in my body that contributed to that nervous system tightness. to let me move more fluidly, i go to a place ik i cant be seen, and i even close my eyes (so i cant worry abt if i look silly, the purpose is literally to be silly) and i listen to music and just move however tf i want. it truly changed my life i could cry thinking abt it honestly. i havent had a panic attack