To reduce anxiety, there’s a technique called the “physiological sigh” which I heard this morning on the free Huberman Lab podcast. Huberman says there is scientific evidence this will reduce anxiety immediately. On today’s (30 October 2023) episode 148, go to 41 minutes and 16 seconds; he describes and demonstrates it.
Take a full breath through your nose, pause a second, then nose breathe in a little more - it’ll sound like a sniff - then slowly exhale through your mouth.
For long-term, to reduce anxiety reaction to stress, he recommends cold plunges or cold showers (at least once a week) and focus on keeping your mind calm while you endure the physical discomfort.

I’m just throwing this info out there in the hopes that it may be useful to someone.