Personally, I manage my severe anxiety by taking a SSRI, Lexapro. It’s been life changing for my anxiety, and therefore indirectly improves my speech too because I’m not so anxious in social settings and meetings etc… I also do the 4-7-8 box breathing technique a few times a day to further reduce that dreaded fight or flight mode in my nervous system. Not everyone likes to go on medication, so each to their own. Do what works for you.