transform function
Returns the geometry transformed from the source CRS to the dest CRS.
Syntax
transform( geom, sAuthId, dAuthId )
Arguments
geom → QgsGeometry
sCrsId → the Source Auth CRS Id
dCrsId → the Dest Auth CRS Id
Example
geomToWKT( transform( $geometry, 'EPSG:2154', 'EPSG:4326' ) ) → POINT(0 51)