In case you somehow aren't familiar, Sam Adams Utopias is an extreme barrel-aged beer from Boston Beer Company that clocks in a 28% — but as it is fermented with water, yeast, hops, and barley, it's indeed a beer by definition.

With that said, Samuel Adams themselves never defines the style beyond "barrel-aged beer." Would you consider it an American Strong Ale, American Barleywine, or even something else completely (like Old Ale)? I did find a poster from Sam Adams at the Denver Rare Beer Tasting where the describe the Utopias On Cherries as a BA Double Bock... which honestly, the hop/malt bill certainly does align with that:

Utopias is made with Samuel Adams two-row pale malt blend, Caramel 60, Munich malts, and noble hops: Spalt Spalter, Hallertau Mittelfrueh, and Tettnang Tettnanger

From an article about doppelbocks:

The bulk of any bock’s grain bill is good German Munich malt, and Doppelbock is no exception. All-grain brewers have no shortage of excellent malt choices, but extract brewers will want to mainly stick to the many excellent Munich extracts now available. Specialty malts are best kept to a minimum, with perhaps a bit of caramel malt and roasted malt to round things out. A decoction mash traditionally delivers additional complexity, but a touch of melanoidin malt is a great time saver at which only the most devoted of purists will scoff. As for hops, a single bittering addition is sufficient. Hallertauer Mittelfrüh and Tettnanger are traditional choices, but Perle and Magnum are also excellent.

Also from the 2017 release of Utopias as per BBC:

The brewers created the final 2017 blend by sampling and blending barrel-aged beer including 24-year-old Triple Bock and 17-year-old Millennium

I think I may have answered my own question. It appear Utopias is closest to a Bock, whether that's double or triple.

But they also say it's an ale. And Bocks are lagers. I don't know.