GDA94 + AHD height - EPSG:9464

WKT

HVCOORDSYS["GDA94_and_AHD_height", 
	GEOGCS["GCS_GDA_1994", 
		DATUM["D_GDA_1994", 
			SPHEROID["GRS_1980", 6378137.0, 298.257222101]], 
		PRIMEM["Greenwich", 0.0], 
		UNIT["Degree", 0.0174532925199433]], 
	VERTCS["AHD", 
		VDATUM["Australian_Height_Datum"], 
		PARAMETER["Vertical_Shift", 0.0], 
		PARAMETER["Direction", 1.0], 
		UNIT["Meter", 1.0]]]

WKT2

COMPOUNDCRS["GDA94_and_AHD_height", 
	GEOGCRS["GCS_GDA_1994", 
		DATUM["D_GDA_1994", 
			ELLIPSOID["GRS_1980", 6378137.0, 298.257222101]], 
		PRIMEM["Greenwich", 0.0], 
		CS[ellipsoidal, 2], 
		AXIS["Latitude (lat)", north, 
			ORDER[1]], 
		AXIS["Longitude (lon)", east, 
			ORDER[2]], 
		ANGLEUNIT["Degree", 0.0174532925199433]], 
	VERTCRS["AHD", 
		VDATUM["Australian_Height_Datum"], 
		CS[vertical, 1], 
		AXIS["Gravity-related height (H)", up, 
			LENGTHUNIT["Meter", 1.0]]], 
	ID["EPSG", "9464"]]

Data from @esri/proj-codes

{
  "wkid": 9464,
  "latestWkid": 9464,
  "pcsWkid": 0,
  "gcsWkid": 4283,
  "vcsWkid": 5711,
  "macro": "PE_HVC_GDA94_AHD_HEIGHT",
  "name": "GDA94_and_AHD_height",
  "wkt": "HVCOORDSYS[\"GDA94_and_AHD_height\",GEOGCS[\"GCS_GDA_1994\",DATUM[\"D_GDA_1994\",SPHEROID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],VERTCS[\"AHD\",VDATUM[\"Australian_Height_Datum\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]]",
  "wkt2": "COMPOUNDCRS[\"GDA94_and_AHD_height\",GEOGCRS[\"GCS_GDA_1994\",DATUM[\"D_GDA_1994\",ELLIPSOID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],CS[ellipsoidal,2],AXIS[\"Latitude (lat)\",north,ORDER[1]],AXIS[\"Longitude (lon)\",east,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433]],VERTCRS[\"AHD\",VDATUM[\"Australian_Height_Datum\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]]],ID[\"EPSG\",\"9464\"]]",
  "description": "GDA94 + AHD height",
  "authority": "EPSG",
  "version": "9.9(12.9.0)",
  "deprecated": "no",
  "areaname": "Australia Christmas and Cocos - onshore",
  "extent": {
    "slat": -43.7,
    "nlat": -9.86,
    "llon": 96.76,
    "rlon": 153.69
  }
}