Branding agency Bold has made several free styleguide templates available to download in InDesign format. Check them out.
Olson Style Guide - Free Download
Design Brand Guidelines, Brand Style Guides, Branding Book Manual, Identity, Corporate Style Guide
Brand Guideline Template designs, themes, templates and
Brand guidelines template Vectors & Illustrations for Free Download
Styleguide Toolbox - Templates, UI Kits, Tools & Generators
Free Brand Guidelines Template (+ Best Tips), Easily Customizable
50 of the best brand style guides to inspire you
Design Brand Guidelines, Brand Style Guides, Branding Book Manual, Identity, Corporate Style Guide
70+ Brand Guidelines Templates, Examples & Tips - Venngage
Page 2 Brand Style Guide Illustrator Template - Free Vectors
Free brand style guides templates - Design Resources - Graphic