1) Breath. We forget to breath when we're anxious which ironically increases anxiety. Vicious cycle. Here's a widget that actually helps that issue: https://www.amazon.com/gp/product/B00TH3SQOI/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
2) How do you get to Carnegie Hall? Practice.
If you dig around some of the content can be found online. This is a program I’m talking about https://www.amazon.com/Vocal-Power-Roger-Love-audiobook/dp/B00OH780H2/ref=mp_s_a_1_4?dchild=1&keywords=roger+love&qid=1599216220&sr=8-4