RGNC15 (lon-lat) + NGNC08 height - EPSG:10318

WKT

HVCOORDSYS["RGNC15_(lon-lat)_and_NGNC08_height", 
	GEOGCS["RGNC15_(lon-lat)", 
		DATUM["Reseau_Geodesique_de_Nouvelle_Caledonie_2015", 
			SPHEROID["GRS_1980", 6378137.0, 298.257222101]], 
		PRIMEM["Greenwich", 0.0], 
		UNIT["Degree", 0.0174532925199433]], 
	VERTCS["NGNC08_height", 
		VDATUM["Nivellement_General_de_Nouvelle_Caledonie_2008"], 
		PARAMETER["Vertical_Shift", 0.0], 
		PARAMETER["Direction", 1.0], 
		UNIT["Meter", 1.0]]]

WKT2

COMPOUNDCRS["RGNC15_(lon-lat)_and_NGNC08_height", 
	GEOGCRS["RGNC15_(lon-lat)", 
		DATUM["Reseau_Geodesique_de_Nouvelle_Caledonie_2015", 
			ELLIPSOID["GRS_1980", 6378137.0, 298.257222101]], 
		PRIMEM["Greenwich", 0.0], 
		CS[ellipsoidal, 2], 
		AXIS["Longitude (lon)", east, 
			ORDER[1]], 
		AXIS["Latitude (lat)", north, 
			ORDER[2]], 
		ANGLEUNIT["Degree", 0.0174532925199433]], 
	VERTCRS["NGNC08_height", 
		VDATUM["Nivellement_General_de_Nouvelle_Caledonie_2008"], 
		CS[vertical, 1], 
		AXIS["Gravity-related height (H)", up, 
			LENGTHUNIT["Meter", 1.0]]], 
	ID["EPSG", "10318"]]

Data from @esri/proj-codes

{
  "wkid": 10318,
  "latestWkid": 10318,
  "pcsWkid": 0,
  "gcsWkid": 10312,
  "vcsWkid": 9351,
  "macro": "PE_HVC_RGNC15_LON_LAT_NGNC08_HEIGHT",
  "name": "RGNC15_(lon-lat)_and_NGNC08_height",
  "wkt": "HVCOORDSYS[\"RGNC15_(lon-lat)_and_NGNC08_height\",GEOGCS[\"RGNC15_(lon-lat)\",DATUM[\"Reseau_Geodesique_de_Nouvelle_Caledonie_2015\",SPHEROID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],VERTCS[\"NGNC08_height\",VDATUM[\"Nivellement_General_de_Nouvelle_Caledonie_2008\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]]",
  "wkt2": "COMPOUNDCRS[\"RGNC15_(lon-lat)_and_NGNC08_height\",GEOGCRS[\"RGNC15_(lon-lat)\",DATUM[\"Reseau_Geodesique_de_Nouvelle_Caledonie_2015\",ELLIPSOID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],CS[ellipsoidal,2],AXIS[\"Longitude (lon)\",east,ORDER[1]],AXIS[\"Latitude (lat)\",north,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433]],VERTCRS[\"NGNC08_height\",VDATUM[\"Nivellement_General_de_Nouvelle_Caledonie_2008\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]]],ID[\"EPSG\",\"10318\"]]",
  "description": "RGNC15 (lon-lat) + NGNC08 height",
  "authority": "EPSG",
  "version": "10.085(13.2.0)",
  "deprecated": "no",
  "areaname": "New Caledonia - Belep, Grande Terre, Ile des Pins, Loyalty Islands",
  "extent": {
    "slat": -22.73,
    "nlat": -19.5,
    "llon": 163.54,
    "rlon": 168.19
  }
}