Son staying in all the time.

Hi, one of our 11yo Son’s Autism traits is severe anxiety about meeting people he knows out of their usual context, for example, school friends out of school. It has got to the point that we struggle to get him to leave the house and he’d rather stay in his bedroom all day. If anyone has experience of something similar, what strategies have you used to help as we’re struggling to know how to help him? Thanks!