Al Pacino’s Jimmy Hoffa is a strong supporting role — he doesn’t appear in The Irishman until the second hour, and there’s about 35 minutes’ of movie left after he departs. Agreed, Pacino’s performance feels like a co-lead but he’s not the main protagonist — Robert DeNiro’s Frank Sheeran has that burden.
Same deal with Brad Pitt’s Cliff Booth in Once Upon A Time in Hollywood. He’s more cool-cat charismatic than Leonardo DiCaprio’s Rick Dalton, but he’s still the best friend, still bunking in that grubby trailer, still the guy driving his boss’s car, etc. Almost a co-lead, granted, but not the lead either. And that’s cool.
Willem Dafoe is definitely a co-lead with RBatz in The Lighthouse.
Jonathan Pryce is unquestionably playing the lead protagonist in The Two Popes — he and Anthony Hopkins are not co-leads.
Tom Hanks’ Fred Rogers obviously has more gravity and personality than Matthew Rhys’ Lloyd Vogel in A Beautiful Day in the Neighborhood, and if Sony had chosen to run him as a lead, they could have sold it. But they decided against that.