There are a number of messaging framework templates available these days. I shared an article that I like to reference (link is below again); I also suggest you check out posts from Andy Raskin (https://andyraskin.com/) who I've worked with previously or check out this recording of Tiffany Spencer doing a talk at Heavybit. It's a handful of years old, but still relevant: https://www.heavybit.com/library/video/getting-to-a-messaging-framework-and-value-prop/.
More than having the right template, however, the critical second piece to the question is about driving home messaging to internal stakeholders. Messaging projects should not be done in a vacuum. As a product marketer, you have the responsibility and superpower to be closest to what's happening in the market, with your buyers, at scale. Take that information, distill it down into insights that are easily digestible and then use that to take your internal stakeholders along for the journey - show them how the messaging you've helped develop is differentiated from your competitors and they will get excited.
Another way to drive messaging home with larger groups is through certifications. Every one of my sales teams has had a certification process and messaging/narrative is definitely a part of that. Align with your sales leadership on this.
https://medium.com/@jamiecatherinebarnett/your-must-have-core-messaging-framework-a-guide-for-high-tech-startups-6eb39a6d0864