Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Export to USD Layer
USDEXPORTER_EXPORT2LAYERParameter: File Format
USDEXPORTER_FILEFORMATParameter: Zipped (*.usdz)
USDEXPORTER_ZIPParameter: Geometry
USDEXPORTER_GEOMETRYParameter: Cameras
USDEXPORTER_CAMERASParameter: Instances
USDEXPORTER_INSTANCESParameter: Materials
USDEXPORTER_MATERIALSParameter: USDEXPORTER_MATERIALS_BRIDGE_INFO
USDEXPORTER_MATERIALS_BRIDGE_INFOParameter: Lights
USDEXPORTER_LIGHTUNITSParameter: Normals
USDEXPORTER_GEOMETRY_NORMALSParameter: UV
USDEXPORTER_GEOMETRY_UVParameter: Vertex Color
USDEXPORTER_GEOMETRY_VERTEXCOLORSParameter: Display Color
USDEXPORTER_GEOMETRY_DISPLAYCOLORParameter: Skin
USDEXPORTER_ANIMATION_SKELETONParameter: Animation Range
USDEXPORTER_ANIMATION_FRAMESParameter: From
USDEXPORTER_ANIMATION_TIMEFROMParameter: To
USDEXPORTER_ANIMATION_TIMETOParameter: Bake Materials
USDEXPORTER_MATERIALS_BAKETEXTURESParameter: Width
USDEXPORTER_MATERIALS_WIDTHParameter: Height
USDEXPORTER_MATERIALS_HEIGHTParameter: Resize Textures
USDEXPORTER_MATERIALS_RESIZEParameter: Format
USDEXPORTER_MATERIALS_FORMATParameter: Format
USDEXPORTER_MATERIALS_FORMAT_USDZParameter: Depth
USDEXPORTER_MATERIALS_DEPTH