United Parcel Service is girding its business against a slowdown in global delivery volumes as it advised that annual revenue could decline for the first time in years. The Atlanta-based delivery company said Tuesday that it expects revenue of between $97 billion and $99.4 billion in 2023, down from $100.3 billion last year. The outlook comes after the company posted a surprise decline in fourth-quarter revenue after delivering fewer items during the holidays than a year earlier.