ETRS89 + MSL UK & Ireland VORF08 depth - EPSG:10156

WKT

HVCOORDSYS["ETRS_1989_and_MSL_UK_Ireland_VORF08_depth", 
	GEOGCS["GCS_ETRS_1989", 
		DATUM["D_ETRS_1989", 
			SPHEROID["GRS_1980", 6378137.0, 298.257222101]], 
		PRIMEM["Greenwich", 0.0], 
		UNIT["Degree", 0.0174532925199433]], 
	VERTCS["MSL_UK_Ireland_VORF08_depth", 
		VDATUM["Mean_Sea_Level_UK_Ireland_VORF08"], 
		PARAMETER["Vertical_Shift", 0.0], 
		PARAMETER["Direction", -1.0], 
		UNIT["Meter", 1.0]]]

WKT2

COMPOUNDCRS["ETRS_1989_and_MSL_UK_Ireland_VORF08_depth", 
	GEOGCRS["GCS_ETRS_1989", 
		DATUM["D_ETRS_1989", 
			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["MSL_UK_Ireland_VORF08_depth", 
		VDATUM["Mean_Sea_Level_UK_Ireland_VORF08"], 
		CS[vertical, 1], 
		AXIS["Gravity-related height (H)", down, 
			LENGTHUNIT["Meter", 1.0]]], 
	ID["EPSG", "10156"]]

Data from @esri/proj-codes

{
  "wkid": 10156,
  "latestWkid": 10156,
  "pcsWkid": 0,
  "gcsWkid": 4258,
  "vcsWkid": 10150,
  "macro": "PE_HVC_ETRS89_MSL_UK_IRELAND_VORF08_DEPTH",
  "name": "ETRS_1989_and_MSL_UK_Ireland_VORF08_depth",
  "wkt": "HVCOORDSYS[\"ETRS_1989_and_MSL_UK_Ireland_VORF08_depth\",GEOGCS[\"GCS_ETRS_1989\",DATUM[\"D_ETRS_1989\",SPHEROID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],VERTCS[\"MSL_UK_Ireland_VORF08_depth\",VDATUM[\"Mean_Sea_Level_UK_Ireland_VORF08\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",-1.0],UNIT[\"Meter\",1.0]]]",
  "wkt2": "COMPOUNDCRS[\"ETRS_1989_and_MSL_UK_Ireland_VORF08_depth\",GEOGCRS[\"GCS_ETRS_1989\",DATUM[\"D_ETRS_1989\",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[\"MSL_UK_Ireland_VORF08_depth\",VDATUM[\"Mean_Sea_Level_UK_Ireland_VORF08\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",down,LENGTHUNIT[\"Meter\",1.0]]],ID[\"EPSG\",\"10156\"]]",
  "description": "ETRS89 + MSL UK & Ireland VORF08 depth",
  "authority": "EPSG",
  "version": "10.077(13.2.0)",
  "deprecated": "no",
  "areaname": "Europe - Ireland and UK offshore",
  "extent": {
    "slat": 47.42,
    "nlat": 63.89,
    "llon": -16.1,
    "rlon": 3.4
  }
}