Styleguides are often developed after the high-fidelity wireframes phase so that you could see what elements you'll need, design them, and then refactor them into a style guide and later into a design system.
When should a style guide be used?
The aim of a style guide is to ensure that multiple contributors work in a cohesive way to reflect your true corporate style and maintain brand consistency with everything from writing to design. Style guides support marketing initiatives by guaranteeing that all messaging is related to your company's goals.
What is a style guide in graphic design?
A style guide is a document that provides guidelines for the way your brand looks in different media, like websites, social media, and so on. Every brand should have their own.