[AndrewHart]

Monzo is another company which does this incredibly well, and wrote a public document on it: https://monzo.com/tone-of-voice/

I'd love to read more on this topic - how companies learn to do this, and then go about establishing it internally, so that it becomes part of their brand and culture.

[tough]

Your comment made me think of mailchimp's https://styleguide.mailchimp.com/voice-and-tone/