ETRS89 + Malin Head height - EPSG:9449

WKT

HVCOORDSYS["ETRS_1989_and_Malin_Head_height", 
	GEOGCS["GCS_ETRS_1989", 
		DATUM["D_ETRS_1989", 
			SPHEROID["GRS_1980", 6378137.0, 298.257222101]], 
		PRIMEM["Greenwich", 0.0], 
		UNIT["Degree", 0.0174532925199433]], 
	VERTCS["Malin_Head", 
		VDATUM["Malin_Head"], 
		PARAMETER["Vertical_Shift", 0.0], 
		PARAMETER["Direction", 1.0], 
		UNIT["Meter", 1.0]]]

WKT2

COMPOUNDCRS["ETRS_1989_and_Malin_Head_height", 
	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["Malin_Head", 
		VDATUM["Malin_Head"], 
		CS[vertical, 1], 
		AXIS["Gravity-related height (H)", up, 
			LENGTHUNIT["Meter", 1.0]]], 
	ID["EPSG", "9449"]]

Data from @esri/proj-codes

{
  "wkid": 9449,
  "latestWkid": 9449,
  "pcsWkid": 0,
  "gcsWkid": 4258,
  "vcsWkid": 5731,
  "macro": "PE_HVC_ETRS89_MALIN_HEAD_HEIGHT",
  "name": "ETRS_1989_and_Malin_Head_height",
  "wkt": "HVCOORDSYS[\"ETRS_1989_and_Malin_Head_height\",GEOGCS[\"GCS_ETRS_1989\",DATUM[\"D_ETRS_1989\",SPHEROID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],VERTCS[\"Malin_Head\",VDATUM[\"Malin_Head\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]]",
  "wkt2": "COMPOUNDCRS[\"ETRS_1989_and_Malin_Head_height\",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[\"Malin_Head\",VDATUM[\"Malin_Head\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]]],ID[\"EPSG\",\"9449\"]]",
  "description": "ETRS89 + Malin Head height",
  "authority": "EPSG",
  "version": "9.8.14(13.2.0)",
  "deprecated": "no",
  "areaname": "Europe - Ireland (Republic and Ulster) - onshore",
  "extent": {
    "slat": 51.39,
    "nlat": 55.43,
    "llon": -10.56,
    "rlon": -5.34
  }
}