.prettierrc with all the common knobs. JSON output drops into .prettierrc, package.json "prettier", or .prettierrc.json.
{
"printWidth": 100,
"tabWidth": 2,
"useTabs": false,
"semi": true,
"singleQuote": false,
"quoteProps": "as-needed",
"trailingComma": "all",
"bracketSameLine": false,
"arrowParens": "always",
"endOfLine": "lf"
}