When I call cameraCharacteristics.get(CONTROL_AE_AVAILABLE_TARGET_FPS_RANGES) on Samsung Galaxy S9 - it returns an array with ranges containing values [15, 15], [24, 24], [7, 30], [15, 30], [30, 30]. I am quite sure that it supports much bigger FPS, or it isn't?
Why does it return such a small ranges?
Most camera devices cannot support high-speed operation with all the features still working. For camera2, there's an explicit constrained high speed mode for 120/240 fps cases.
60fps is generally supported via normal mode, but it's always possible a manufacturer only exposes it in their custom camera app, usually due to performance or power constraints that make it difficult to support for all 3rd-party apps.