VERONA, Italy—The Verona Arena amphitheater in northern Italy has returned to staging full operas for the first time since the pandemic—but with one big difference. The monumental sets that normally fill the vast amphitheater stage have been replaced by dynamic, 3D images broadcast on huge LED screens, recreating a Sicilian village or a Fellini-esque film backlot. Distancing rules meant that stagehands moving sets had to be limited in the cramped backstage in the open-air Roman-era amphitheater, setting in motion a reimagining of the 98th Verona Arena Opera Festival. For this season, technology is standing in for the sets for which the arena is famous, ones big enough to fill the vast stage and engage even audience members sitting far away in the uppermost seats. “We understood already last year in November that we needed to have another plan, in the eventuality that we couldn’t use the big sets,’’ said the …