Voice and design should make the same promise
A strong verbal identity and visual identity system make the same brand promise, even when they use different tools. If the design is calm, precise and understated, busy or overly ornate language can pull the experience in the opposite direction. If the words challenge convention, the visual expression needs enough energy to carry that point of view.
The aim is not to make every brand touchpoint look and sound identical. The aim is to give website content, sales decks, product communications, social posts and customer materials a shared character, mood and set of values. Language can make an idea clear, while design makes that idea easier to feel and remember. Together, they help people understand not only what an organisation does, but what it stands for.
The useful test is simple: could the copy belong to the design, and could the design belong to the words? If the answer is no, the brand experience needs a closer look.
Sources: No creator is an island, Creating connections through design, WellSaid: Shaping the voice of an ethical AI leader