Greek (Athens) - EPSG:4815

WKT

GEOGCS["GCS_Greek_Athens", 
	DATUM["D_Greek", 
		SPHEROID["Bessel_1841", 6377397.155, 299.1528128]], 
	PRIMEM["Athens", 23.7163375], 
	UNIT["Degree", 0.0174532925199433]]

WKT2

GEOGCRS["GCS_Greek_Athens", 
	DATUM["D_Greek", 
		ELLIPSOID["Bessel_1841", 6377397.155, 299.1528128]], 
	PRIMEM["Athens", 23.7163375, 
		ANGLEUNIT["Degree", 0.0174532925199433]], 
	CS[ellipsoidal, 2], 
	AXIS["Latitude (lat)", north, 
		ORDER[1]], 
	AXIS["Longitude (lon)", east, 
		ORDER[2]], 
	ANGLEUNIT["Degree", 0.0174532925199433], 
	ID["EPSG", "4815"]]

Data from @esri/proj-codes

{
  "wkid": 4815,
  "latestWkid": 4815,
  "macro": "PE_GCS_GREEK_ATHENS",
  "name": "GCS_Greek_Athens",
  "wkt": "GEOGCS[\"GCS_Greek_Athens\",DATUM[\"D_Greek\",SPHEROID[\"Bessel_1841\",6377397.155,299.1528128]],PRIMEM[\"Athens\",23.7163375],UNIT[\"Degree\",0.0174532925199433]]",
  "wkt2": "GEOGCRS[\"GCS_Greek_Athens\",DATUM[\"D_Greek\",ELLIPSOID[\"Bessel_1841\",6377397.155,299.1528128]],PRIMEM[\"Athens\",23.7163375,ANGLEUNIT[\"Degree\",0.0174532925199433]],CS[ellipsoidal,2],AXIS[\"Latitude (lat)\",north,ORDER[1]],AXIS[\"Longitude (lon)\",east,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433],ID[\"EPSG\",\"4815\"]]",
  "description": "Greek (Athens)",
  "authority": "EPSG",
  "version": "4.5(4.0.0)",
  "deprecated": "no",
  "areaname": "Greece - onshore",
  "extent": {
    "slat": 34.88,
    "nlat": 41.75,
    "llon": 19.57,
    "rlon": 28.3
  }
}