Could you share any resources you've used to learn it?

I've been part of two Toastmaster's clubs. I've found the Toastmasters program for learning how to speak publicly to be thorough, thoughtful, and easy to get started with. I've found the people in both clubs (different eras, different places) to be friendly, creative, fun, and supportive. I'd recommend Toastmasters to anyone interested in learning public speaking.

Unsolicited advice: my take is this is necessarily something you can only learn interacting with people.

Joing a theatre performance group is one way of achieving it.