QGIS/resources/function_help/json/transform

{
  "function": "transform",
  "description": "Returns the geometry transformed from a source CRS to a destination CRS.",
  "arguments": [ {"arg":"geom","description":"a geometry"},
  {"arg":"source_auth_id","description":"the source auth CRS ID"},
  {"arg":"dest_auth_id","description":"the destination auth CRS ID"}
  ],
  "examples": [ { "expression":"geom_to_wkt( transform( $geometry, 'EPSG:2154', 'EPSG:4326' ) )", "returns":"POINT(0 51)"}
  ]
}