GNTRANS height - EPSG:9923

WKT

VERTCS["GNTRANS_height", 
	VDATUM["GNTRANS"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["GNTRANS_height", 
	VDATUM["GNTRANS"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "9923"]]

Data from @esri/proj-codes

{
  "wkid": 9923,
  "latestWkid": 9923,
  "macro": "PE_VCS_GNTRANS_HEIGHT",
  "name": "GNTRANS_height",
  "wkt": "VERTCS[\"GNTRANS_height\",VDATUM[\"GNTRANS\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"GNTRANS_height\",VDATUM[\"GNTRANS\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"9923\"]]",
  "description": "GNTRANS height",
  "authority": "EPSG",
  "version": "10.042(13.1.0)",
  "deprecated": "no",
  "areaname": "Germany - onshore",
  "extent": {
    "slat": 47.27,
    "nlat": 55.09,
    "llon": 5.86,
    "rlon": 15.04
  }
}