"Flagship franchise" refers to a highly important and successful series or collection of products that significantly represents and leads a company or brand in terms of popularity, sales, and reputation. Full definition
Developer hiring production staff for next chapter of flagship franchise ahead of Hideo Kojima's expected departure (mcvuk.com)
Many of Mario's fellow Nintendo properties, including The Legend of Zelda, Star Fox, F - Zero, Pokémon, Kirby, and Animal Crossing, have referenced the company's flagship franchise in very notable ways. (mariowiki.com)
With the best story since Abyss and the best cast of characters since Vesperia, Tales of Berseria is the best entry in Bandai Namco's flagship franchise for years. (metacritic.com)