Lagos 1955 - EPSG:5796

WKT

VERTCS["Lagos_1955", 
	VDATUM["Lagos_1955"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["Lagos_1955", 
	VDATUM["Lagos_1955"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "5796"]]

Data from @esri/proj-codes

{
  "wkid": 5796,
  "latestWkid": 5796,
  "macro": "PE_VCS_LAGOS_1955",
  "name": "Lagos_1955",
  "wkt": "VERTCS[\"Lagos_1955\",VDATUM[\"Lagos_1955\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"Lagos_1955\",VDATUM[\"Lagos_1955\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"5796\"]]",
  "description": "Lagos 1955",
  "authority": "EPSG",
  "version": "6.15(9.3.0.0)",
  "deprecated": "no",
  "areaname": "Nigeria - onshore",
  "extent": {
    "slat": 4.22,
    "nlat": 13.9,
    "llon": 2.69,
    "rlon": 14.65
  }
}