When Pokémon Legends: Arceus was originally revealed, the way it was described gave many the impression that it was going to be an Open World Game like The Legend of Zelda: Breath of the Wild, and PR and early footage of the game did give this impression. However, this is not actually going to be the case after all.
The Pokémon Company has shared a statement clarifying that the game will be more akin to segmented areas, ( kind of like Monster Hunter), and that the player as the trainer will set out from the village to “various open areas” of the Hisui region to complete tasks.
“In Pokémon Legends: Arceus, Jubilife Village will serve as the base for surveying missions. After receiving an assignment or a request and preparing for their next excursion, players will set out from the village to study one of the various open areas of the Hisui region. After they finish the survey work, players will need to return once more to prepare for their next task. We look forward to sharing more information about exploring the Hisui region soon.”