According to Backstage, The King will have a 3 month shoot:
Netflix feature “The King” is confirmed to start shooting in June. The film is written by Joel Edgerton, who co-stars alongside Timothée Chalamet as King Henry V of England, enduring the battle of Agincourt. Filming begins in June. The production will spend three weeks in England and nine in Hungary. Des Hamilton Casting is onboard.