SRB_ETRS89 3D - EPSG:8684

WKT

GEOGCS["SRB_ETRS89_3D", 
	DATUM["Serbian_Spatial_Reference_System_2000", 
		SPHEROID["GRS_1980", 6378137.0, 298.257222101]], 
	PRIMEM["Greenwich", 0.0], 
	UNIT["Degree", 0.0174532925199433], 
	LINUNIT["Meter", 1.0]]

WKT2

GEOGCRS["SRB_ETRS89_3D", 
	DATUM["Serbian_Spatial_Reference_System_2000", 
		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", "8684"]]

Data from @esri/proj-codes

{
  "wkid": 8684,
  "latestWkid": 8684,
  "macro": "PE_GCS_SRB_ETRS89_3D",
  "name": "SRB_ETRS89_3D",
  "wkt": "GEOGCS[\"SRB_ETRS89_3D\",DATUM[\"Serbian_Spatial_Reference_System_2000\",SPHEROID[\"GRS_1980\",6378137.0,298.257222101]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433],LINUNIT[\"Meter\",1.0]]",
  "wkt2": "GEOGCRS[\"SRB_ETRS89_3D\",DATUM[\"Serbian_Spatial_Reference_System_2000\",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\",\"8684\"]]",
  "description": "SRB_ETRS89 3D",
  "authority": "EPSG",
  "version": "9.5(12.7.0)",
  "deprecated": "no",
  "areaname": "Serbia",
  "extent": {
    "slat": 42.23,
    "nlat": 46.19,
    "llon": 18.81,
    "rlon": 23.01
  }
}