BTRS LO21 - ESRI:112220

WKT

PROJCS["BTRS_LO21", 
	GEOGCS["BTRS", 
		DATUM["BTRS", 
			SPHEROID["Clarke_1880_Arc", 6378249.145, 293.466307656]], 
		PRIMEM["Greenwich", 0.0], 
		UNIT["Degree", 0.0174532925199433]], 
	PROJECTION["Transverse_Mercator"], 
	PARAMETER["False_Easting", 0.0], 
	PARAMETER["False_Northing", 0.0], 
	PARAMETER["Central_Meridian", 21.0], 
	PARAMETER["Scale_Factor", 1.0], 
	PARAMETER["Latitude_Of_Origin", 0.0], 
	UNIT["Meter", 1.0]]

WKT2

PROJCRS["BTRS_LO21", 
	BASEGEOGCRS["BTRS", 
		DATUM["BTRS", 
			ELLIPSOID["Clarke_1880_Arc", 6378249.145, 293.466307656]], 
		PRIMEM["Greenwich", 0.0], 
		CS[ellipsoidal, 2], 
		AXIS["Longitude (lon)", east, 
			ORDER[1]], 
		AXIS["Latitude (lat)", north, 
			ORDER[2]], 
		ANGLEUNIT["Degree", 0.0174532925199433]], 
	CONVERSION["Transverse_Mercator", 
		METHOD["Transverse_Mercator"], 
		PARAMETER["False_Easting", 0.0], 
		PARAMETER["False_Northing", 0.0], 
		PARAMETER["Central_Meridian", 21.0], 
		PARAMETER["Scale_Factor", 1.0], 
		PARAMETER["Latitude_Of_Origin", 0.0]], 
	CS[Cartesian, 2], 
	AXIS["Easting (X)", east, 
		ORDER[1]], 
	AXIS["Northing (Y)", north, 
		ORDER[2]], 
	LENGTHUNIT["Meter", 1.0], 
	ID["Esri", "112220"]]

Data from @esri/proj-codes

{
  "wkid": 112220,
  "latestWkid": 112220,
  "gcsWkid": 104032,
  "macro": "PE_PCS_BTRS_LO21",
  "name": "BTRS_LO21",
  "wkt": "PROJCS[\"BTRS_LO21\",GEOGCS[\"BTRS\",DATUM[\"BTRS\",SPHEROID[\"Clarke_1880_Arc\",6378249.145,293.466307656]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Transverse_Mercator\"],PARAMETER[\"False_Easting\",0.0],PARAMETER[\"False_Northing\",0.0],PARAMETER[\"Central_Meridian\",21.0],PARAMETER[\"Scale_Factor\",1.0],PARAMETER[\"Latitude_Of_Origin\",0.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "PROJCRS[\"BTRS_LO21\",BASEGEOGCRS[\"BTRS\",DATUM[\"BTRS\",ELLIPSOID[\"Clarke_1880_Arc\",6378249.145,293.466307656]],PRIMEM[\"Greenwich\",0.0],CS[ellipsoidal,2],AXIS[\"Longitude (lon)\",east,ORDER[1]],AXIS[\"Latitude (lat)\",north,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433]],CONVERSION[\"Transverse_Mercator\",METHOD[\"Transverse_Mercator\"],PARAMETER[\"False_Easting\",0.0],PARAMETER[\"False_Northing\",0.0],PARAMETER[\"Central_Meridian\",21.0],PARAMETER[\"Scale_Factor\",1.0],PARAMETER[\"Latitude_Of_Origin\",0.0]],CS[Cartesian,2],AXIS[\"Easting (X)\",east,ORDER[1]],AXIS[\"Northing (Y)\",north,ORDER[2]],LENGTHUNIT[\"Meter\",1.0],ID[\"Esri\",\"112220\"]]",
  "description": "BTRS LO21",
  "authority": "Esri",
  "version": "13.6.0",
  "deprecated": "no",
  "areaname": "Botswana - West of 22~E",
  "extent": {
    "slat": -26.88,
    "nlat": -18,
    "llon": 19.99,
    "rlon": 22.01
  }
}