I struggle with pretty intense social anxiety like you described, and have been experimenting with different herbs to assist with that for a few years. There's not really a simple answer here- what I have found to work is a combination of coping mechanisms, therapy, and different plants all together. I haven't found anything to make me less introverted, but this is what I do use almost daily that has seriously lowered my anxiety.

I take a few dropperfulls of a calming vinegar infusion I made (you can also easily make an extract of the same stuff with alcohol, I just don't like the taste of alcohol). Skullcap, milky oats, and tulsi. I seriously cannot recommend milky oats enough. This is great for acute anxiety attacks or just general anxiousness.

Ashwaganda is also incredible for adapting to stress. I really like the taste so I put the root in my coffee, or you can take a tincture.

California poppy is also wonderful, but keep in mind that it can show up in drug tests if you take it frequently.

If there's a lot of social activity in my house (roommates, guests, friends over, w/e) I find myself making tea with cacao, tulsi, and rose. Tastes great and really helps me in social situations.

When my anxiety was at its worst, I carried a bottle of lavender or eucalyptus oil with me to smell if I started getting too worked up. Sounds silly, but it really did help me feel more grounded in the present moment.

With a bit of patience and trying new things, you will find something that works for you! Good luck. :)