Corenswet is leading the Superman cast list, and it sounds like he and James Gunn have methodically thought out the way they wanted to bring the title character to life. As the Hollywood actor shared, that "third character" comes into play with Clark's parents, as well as Rachel Brosnahan's Lois Lane. As he shared:

The day was June 24, 2024 and io9 was in Cleveland to watch the filming of James Gunn’s Superman. At the end of a giant battle over the streets of Metropolis, the Man of Steel knelt down to kiss and profess his love to an inanimate object that special effects would later transform into his dog,

The Authority movie was part of January 2023's initial slate announcement for the DCU but it sounds like the film is still pretty far off despite the fact that The Engineer appears in Superman.