I like to put things out or have ongoing projects available... to occupy the hands and mind . . .to take the pressure off of people feeling the need to talk. It's works for both adults and children.
It can as simple as blocks or puzzles, or a bowl of acorns or marbles, or beeswax or slime, and more!
And while doing, there will usually be some kind of chatter. It may be something as simple as "please pass the red piece" but it is a start. . . to fill the silence and lift the burden of making conversation.
And sometimes we invite a few kids over for a special project or seasonal craft. . . like carving pumpkins!
Noone *has to* say anything, but in the course of the task, conversation does start and people start feeling more comfortable.
Spending time, with no pressure or expectation, allows for conversation. . . and friendship... to flourish.