I also meant the social anxiety aspect. First by doing more interviews you should improve (speaking from experience).

You certainly could pay for a coach.

You could also do interviews as a (would-be) employee of a consulting company, which is very common in EU. Usually the commercial manager will coach you, review your resume and come with you at the interview as an ally.

You could do amateur acting, or engage in a non profit, that involves being in contact with a variety of people.