Canon is that all deck plating has embedded various graviton generators. This is separate from the inertial dampening and structural integrity fields. There’s no single canon idea on how they work though (for obvious reasons) so there’s examples of a single generator that can be disabled, or many miniature ones through that are independent. Maybe that design is the one seen where a room or deck can be customized to a different pull than others. The holodecks probably use a much more advanced version along with other tractor beams to create the many forces needed for simulations.

But the best grav generator won’t save you if the inertial dampeners fail to dampen at a crucial point.