Mouthful Mode is a new gameplay mechanic specific to Kirby and the Forgotten Land. Instead of inhaling an enemy, absorbing their powers, and then spitting them out (like Kirby traditionally does), Mouthful Mode allows our little pink friend to quite literally consume a large object.
Kirby’s mouth will fully engulf whatever object you’re targeting, giving you complete control over it. Think cars, vending machines, traffic cones, and even more.
Source: https://www.distractify.com/p/what-is-mouthful-mode-kirby-and-forgotten-land