Designers involved in such projects work with logos, typography, image library, color scheme, business cards, corporate letterheads and other visual components of the brand.
To preserve the branding theme, designers are developing a style guide. With their help, all products and visual representations of the brand maintain the unity of style, supporting the basic concept.
These can be:
Logotype.
Brand design system (colors, fonts, background, elements, style, illustrations, etc.)
Brandbook.
Mockups for all of this.