Google sheets advanced service v4 exposed via endpoints abstractions.
Add as library with id 1eKqiWDenWj5yAVBd6WXJkEqFOyFDji7Iean7u4pVJWTWhKUmRIeNGsqN
function myFunction () {
const endpoints = GSheetEndpoints.fromId(id);
const spreadsheetResource = endpoints.spreadsheet.get();
Logger.log(spreadsheetResource.properties.timeZone);
}Further documentation on its usage.