Editorial style guide (house style)
Your team's written-down rulings on spelling, capitalization, numbers, and product terms, so five writers sound like one.
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What it is
An editorial style guide is the written-down set of rulings your team follows on spelling, capitalization, numbers, punctuation, and product terms. Its real job is settling arguments once instead of every review cycle. Almost nobody writes one from scratch: you adopt a base (AP, Chicago, the Microsoft Writing Style Guide, or the Google developer documentation style guide) and then record only your house exceptions on top.
The useful shape is three short sections: base guide plus deviations (sentence case for headings, Oxford comma yes, en dash never), a product term list with the approved spelling of every feature name, and a small do/don't table for the calls people keep getting wrong ('sign in' as a verb, 'sign-in' as a noun). Mailchimp's public content style guide is the canonical example of this done well.
Gotcha: a 60-page guide nobody reads changes nothing. Keep the decisions page to one screen, put the term list where writers already work, and encode what you can into a linter (Vale, textlint) so the rules enforce themselves. A style guide is not a grammar course; anything that is just correct English does not belong in it.
Ask AI for it
Draft a one-page editorial style guide for [product]. Use the Microsoft Writing Style Guide as the default base, then apply [house decisions] and [approved product terms with variants] on top of it. Where no house decision is supplied, inherit the base guide and say so rather than inventing a ruling. Include: (1) a decisions table (heading case, Oxford comma, dashes, numerals vs words, date and time format, contractions, second person), (2) a product terminology list with the approved spelling and the banned variants for each feature name, built only from the supplied terms, (3) a do/don't table of 10 calls writers get wrong, each with a right example and a wrong example. End with a 'needs a decision' list of every product term or conflict the inputs did not resolve. Give rulings, not explanations, and leave out anything that is simply standard English.