IGS08 - ESRI:104010

WKT

GEOGCS["GCS_IGS08", 
	DATUM["IGS08", 
		SPHEROID["GRS_1980", 6378137.0, 298.257222101]], 
	PRIMEM["Greenwich", 0.0], 
	UNIT["Degree", 0.0174532925199433]]

WKT2

GEOGCRS["GCS_IGS08", 
	DYNAMIC[
		FRAMEEPOCH[2005.0], 
		MODEL["ITRF2008-PMM"]], 
	DATUM["IGS08", 
		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], 
	ID["Esri", "9014"]]

Data from @esri/proj-codes

{
  "wkid": 104010,
  "latestWkid": 9014,
  "macro": "PE_GCS_IGS08",
  "name": "GCS_IGS08",
  "wkt": "GEOGCS[\"GCS_IGS08\",DATUM[\"IGS08\",SPHEROID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]]",
  "wkt2": "GEOGCRS[\"GCS_IGS08\",DYNAMIC[FRAMEEPOCH[2005.0],MODEL[\"ITRF2008-PMM\"]],DATUM[\"IGS08\",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],ID[\"Esri\",\"9014\"]]",
  "description": "IGS08",
  "authority": "Esri",
  "version": "10.4.0",
  "deprecated": "codechange",
  "areaname": "World",
  "extent": {
    "slat": -90,
    "nlat": 90,
    "llon": -180,
    "rlon": 180
  },
  "frameEpoch": 2005,
  "deformationModel": "ITRF2008-PMM"
}