ST_GeometryN

Introduction: Return the 0-based Nth geometry if the geometry is a GEOMETRYCOLLECTION, (MULTI)POINT, (MULTI)LINESTRING, MULTICURVE or (MULTI)POLYGON. Otherwise, return null

Format: ST_GeometryN(geom: geometry, n: Int)

SQL example:

SELECT ST_GeometryN(ST_GeomFromText('MULTIPOINT((1 2), (3 4), (5 6), (8 9))'), 1)

Output: POINT (3 4)