Use the Layers button in the top right corner to turn whole groups of objects on or off at once, like all floors, all ductwork, or the entire mechanical model.
Opening the panel
Tap the button to the right of Measure in the top right corner. What it's called depends on your model:
Layers: For a single model, you'll see its categories, such as Walls, Floors, Doors, Structural Framing, and Specialty Equipment.
Models: For a federated model, you'll see each discipline model, such as Architectural, Structural, Mechanical, and Electrical, along with its file name.
Turning a layer off or on
Tap the eye icon next to any layer or model to hide it. The row turns gray and everything in it disappears from the model. Tap the eye again to show it.
For example, turn off Floors to see utilities below the slab, or turn off Architectural to see only the MEP systems.
Showing everything again
When any layer is off, a Show all button appears at the top of the panel. Tap it to turn every layer back on.
Tips
To close the panel, tap the Layers (or Models) button again, or tap anywhere in the model.
Layers hide whole groups. To hide a single object, tap it instead. See Hiding Objects in Resolve Field. Layers you turn off reset when you leave the model and open it again.
Long lists scroll, so swipe up in the panel if you don't see the layer you need.