NAD 1927 UTM Zone 21N - EPSG:26721

WKT

PROJCS["NAD_1927_UTM_Zone_21N", 
	GEOGCS["GCS_North_American_1927", 
		DATUM["D_North_American_1927", 
			SPHEROID["Clarke_1866", 6378206.4, 294.9786982]], 
		PRIMEM["Greenwich", 0.0], 
		UNIT["Degree", 0.0174532925199433]], 
	PROJECTION["Transverse_Mercator"], 
	PARAMETER["False_Easting", 500000.0], 
	PARAMETER["False_Northing", 0.0], 
	PARAMETER["Central_Meridian", -57.0], 
	PARAMETER["Scale_Factor", 0.9996], 
	PARAMETER["Latitude_Of_Origin", 0.0], 
	UNIT["Meter", 1.0]]

WKT2

PROJCRS["NAD_1927_UTM_Zone_21N", 
	BASEGEOGCRS["GCS_North_American_1927", 
		DATUM["D_North_American_1927", 
			ELLIPSOID["Clarke_1866", 6378206.4, 294.9786982]], 
		PRIMEM["Greenwich", 0.0], 
		CS[ellipsoidal, 2], 
		AXIS["Latitude (lat)", north, 
			ORDER[1]], 
		AXIS["Longitude (lon)", east, 
			ORDER[2]], 
		ANGLEUNIT["Degree", 0.0174532925199433]], 
	CONVERSION["Transverse_Mercator", 
		METHOD["Transverse_Mercator"], 
		PARAMETER["False_Easting", 500000.0], 
		PARAMETER["False_Northing", 0.0], 
		PARAMETER["Central_Meridian", -57.0], 
		PARAMETER["Scale_Factor", 0.9996], 
		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["EPSG", "26721"]]

Data from @esri/proj-codes

{
  "wkid": 26721,
  "latestWkid": 26721,
  "gcsWkid": 4267,
  "macro": "PE_PCS_NAD_1927_UTM_21N",
  "name": "NAD_1927_UTM_Zone_21N",
  "wkt": "PROJCS[\"NAD_1927_UTM_Zone_21N\",GEOGCS[\"GCS_North_American_1927\",DATUM[\"D_North_American_1927\",SPHEROID[\"Clarke_1866\",6378206.4,294.9786982]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Transverse_Mercator\"],PARAMETER[\"False_Easting\",500000.0],PARAMETER[\"False_Northing\",0.0],PARAMETER[\"Central_Meridian\",-57.0],PARAMETER[\"Scale_Factor\",0.9996],PARAMETER[\"Latitude_Of_Origin\",0.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "PROJCRS[\"NAD_1927_UTM_Zone_21N\",BASEGEOGCRS[\"GCS_North_American_1927\",DATUM[\"D_North_American_1927\",ELLIPSOID[\"Clarke_1866\",6378206.4,294.9786982]],PRIMEM[\"Greenwich\",0.0],CS[ellipsoidal,2],AXIS[\"Latitude (lat)\",north,ORDER[1]],AXIS[\"Longitude (lon)\",east,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433]],CONVERSION[\"Transverse_Mercator\",METHOD[\"Transverse_Mercator\"],PARAMETER[\"False_Easting\",500000.0],PARAMETER[\"False_Northing\",0.0],PARAMETER[\"Central_Meridian\",-57.0],PARAMETER[\"Scale_Factor\",0.9996],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[\"EPSG\",\"26721\"]]",
  "description": "NAD 1927 UTM Zone 21N",
  "authority": "EPSG",
  "version": "7.8.2(3.0.1)",
  "deprecated": "no",
  "areaname": "Canada - 60~W to 54~W and NAD27",
  "extent": {
    "slat": 40.57,
    "nlat": 68.93,
    "llon": -60,
    "rlon": -54
  }
}