Specific strategies for dialogue first draft?

Right now my biggest road-block is finding something for my characters to say. When in new situations or around strangers, I usually default to staying quiet, so I'm having a hard time organically coming up with things for my characters to say.

Do you have any strategies or formulas for coming up with conversation topics, responses, etc? Even if it's really basic or reductive a starting point to practice would help a lot.

Edit: also any resources for learning the basics would be appreciated. Every time I try to research this on my own it's a bunch of posts and videos about how to improve dialogue, or the goals of good dialogue. They all assume you have some dialogue already written to improve upon.