Boxy is back and business is booming. Retro SUVs like the Jeep Wrangler are big—literally and figuratively. The off-road icon has endured for more than 70 years, but a chief rival has arrived just in time to challenge the king of off-road SUVs. The 2021 Ford Bronco sets its sights squarely on the 2020 Wrangler’s right-angle frame and...