ISN 1993 3D - EPSG:4945

WKT

GEOGCS["ISN_1993_3D", 
	DATUM["D_Islands_Network_1993", 
		SPHEROID["GRS_1980", 6378137.0, 298.257222101]], 
	PRIMEM["Greenwich", 0.0], 
	UNIT["Degree", 0.0174532925199433], 
	LINUNIT["Meter", 1.0]]

WKT2

GEOGCRS["ISN_1993_3D", 
	DATUM["D_Islands_Network_1993", 
		ELLIPSOID["GRS_1980", 6378137.0, 298.257222101]], 
	PRIMEM["Greenwich", 0.0], 
	CS[ellipsoidal, 3], 
	AXIS["Latitude (lat)", north, 
		ORDER[1], 
		ANGLEUNIT["Degree", 0.0174532925199433]], 
	AXIS["Longitude (lon)", east, 
		ORDER[2], 
		ANGLEUNIT["Degree", 0.0174532925199433]], 
	AXIS["Ellipsoidal height (h)", up, 
		ORDER[3], 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "4945"]]

Data from @esri/proj-codes

{
  "wkid": 4945,
  "latestWkid": 4945,
  "macro": "PE_GCS_ISN_1993_3D",
  "name": "ISN_1993_3D",
  "wkt": "GEOGCS[\"ISN_1993_3D\",DATUM[\"D_Islands_Network_1993\",SPHEROID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433],LINUNIT[\"Meter\",1.0]]",
  "wkt2": "GEOGCRS[\"ISN_1993_3D\",DATUM[\"D_Islands_Network_1993\",ELLIPSOID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],CS[ellipsoidal,3],AXIS[\"Latitude (lat)\",north,ORDER[1],ANGLEUNIT[\"Degree\",0.0174532925199433]],AXIS[\"Longitude (lon)\",east,ORDER[2],ANGLEUNIT[\"Degree\",0.0174532925199433]],AXIS[\"Ellipsoidal height (h)\",up,ORDER[3],LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"4945\"]]",
  "description": "ISN 1993 3D",
  "authority": "EPSG",
  "version": "6.14(12.7.0)",
  "deprecated": "no",
  "areaname": "Iceland",
  "extent": {
    "slat": 59.96,
    "nlat": 69.59,
    "llon": -30.87,
    "rlon": -5.55
  }
}