CH1903 - EPSG:4149

WKT

GEOGCS["GCS_CH1903", 
	DATUM["D_CH1903", 
		SPHEROID["Bessel_1841", 6377397.155, 299.1528128]], 
	PRIMEM["Greenwich", 0.0], 
	UNIT["Degree", 0.0174532925199433]]

WKT2

GEOGCRS["GCS_CH1903", 
	DATUM["D_CH1903", 
		ELLIPSOID["Bessel_1841", 6377397.155, 299.1528128]], 
	PRIMEM["Greenwich", 0.0], 
	CS[ellipsoidal, 2], 
	AXIS["Latitude (lat)", north, 
		ORDER[1]], 
	AXIS["Longitude (lon)", east, 
		ORDER[2]], 
	ANGLEUNIT["Degree", 0.0174532925199433], 
	ID["EPSG", "4149"]]

Data from @esri/proj-codes

{
  "wkid": 4149,
  "latestWkid": 4149,
  "macro": "PE_GCS_CH1903",
  "name": "GCS_CH1903",
  "wkt": "GEOGCS[\"GCS_CH1903\",DATUM[\"D_CH1903\",SPHEROID[\"Bessel_1841\",6377397.155,299.1528128]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]]",
  "wkt2": "GEOGCRS[\"GCS_CH1903\",DATUM[\"D_CH1903\",ELLIPSOID[\"Bessel_1841\",6377397.155,299.1528128]],PRIMEM[\"Greenwich\",0.0],CS[ellipsoidal,2],AXIS[\"Latitude (lat)\",north,ORDER[1]],AXIS[\"Longitude (lon)\",east,ORDER[2]],ANGLEUNIT[\"Degree\",0.0174532925199433],ID[\"EPSG\",\"4149\"]]",
  "description": "CH1903",
  "authority": "EPSG",
  "version": "6.5(8.1.0)",
  "deprecated": "no",
  "areaname": "Europe - Liechtenstein and Switzerland",
  "extent": {
    "slat": 45.81,
    "nlat": 47.81,
    "llon": 5.95,
    "rlon": 10.5
  }
}