Having some understanding of the nature of the anxiety can help in narrowing down options. Though your friend would be best served with a wholistic approach over a magical one. [Wholistic, as in treating the whole person, as opposed to holistic which is something else] .
Moving forward through these kinds of challenges are a journey, not a light switch. Accredited psychological support would be the first suggestion. Then perhaps shadow-working and meditation to explore where this anxiety comes from once your friend has developed a bit of an emotional foundation.
As far as managing anxiety in the moment, help her find some sort of affirmations that help, which she can remind herself of when she starts feeling things build up so they don't become overwhelming. For some having something at hand like a worry stone, fidget spinner, stress balls, or a 'soothie' like a small bit of ribbon helps. Something small enough to hold in a hand and fiddle with and use to have something familiar and comforting.