I recently read Ron Chernow's Alexander Hamilton biography and found a strategy for becoming a better speaker.
Read and write a lot. Speaking is really just the ability to succinctly convey ideas (that you get from books). Writing helps you make sense of the books and combine ideas.
Starting a blog helps too – people can give you feedback on how good or bad your ideas are.
The Alexander Hamilton strategy: Hamilton would go on walks and talk to himself about all the things he learned from reading books.
I did this a few years ago and it worked well. Make sure to put Airpods in so people don't think you're crazy.
Start a YouTube channel. This teaches you how to speak well in the most useful place – the internet. It also allows you to get feedback – if you're terrible, your audience will let you know (either by a lack of views or in the comments). This is essential for gauging what level your skills are at. Everyone starts out being terrible at speaking on video. Watch this video of Elliot Choy. When he started YouTube, he was terrible at speaking. But now he's good at speaking and has 1 million subscribers.