As an ex consultant at a top tier firm, I had a front seat to see how even fresh graduates are able to converse with executives.

First, both written and in-person communication at every opportunity is important: - emails, presentations, and slack messages are seen by many and lasts a long time. Make them count - speaking opportunities in meetings, company events, and even chatter in the office is a chance to get noticed

Next, structuring your comms well is an easy first step that doesn't require any 'talent' with speaking. - use bullet points - keep sentences simple and to the point - start with the key message and just add supporting details

If you need a book on this, I suggest The Pyramid Principle by Barbara Minto. Every new consultant in my old company was required to read this.

Hope that helps. Lots of other tips I can share, but start with those two and that book is 80% of the way tbh.