Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: File Format
GLTFEXPORTER_FILEFORMAT
Parameter: Current Frame
GLTFEXPORTER_CURRENTFRAME
Parameter: Custom Frame
GLTFEXPORTER_CUSTOMFRAME
Parameter: Transform
GLTFEXPORTER_PSRANIMATIONS
Parameter: Morph
GLTFEXPORTER_MORPHANIMATIONS
Parameter: Skin
GLTFEXPORTER_SKINANIMATIONS
Parameter: Bake Animation
GLTFEXPORTER_BAKEANIMATIONS
Parameter: Textures
GLTFEXPORTER_TEXTURES
Parameter: Width
GLTFEXPORTER_TEXTURES_WIDTH
Parameter: Height
GLTFEXPORTER_TEXTURES_HEIGHT
Parameter: Resize Textures
GLTFEXPORTER_TEXTURES_RESIZE
Parameter: Double Sided
GLTFEXPORTER_DOUBLESIDED
Parameter: Cameras
GLTFEXPORTER_CAMERAS
Parameter: Instances
GLTFEXPORTER_INSTANCES
Parameter: Normals
GLTFEXPORTER_NORMALS
Parameter: UVs
GLTFEXPORTER_UVS
Parameter: Flip Z
GLTFEXPORTER_FLIPZ