The cells are returned together so their relative sizes remain visible in a shared coordinate frame.
SELECT ST_GeomFromGeoHash('9qqj7nmxncgyy4d0dbxqz0', 4) AS "precision 4", ST_GeomFromGeoHash('9qqj7nmxncgyy4d0dbxqz0', 5) AS "precision 5", ST_GeomFromGeoHash('9qqj7nmxncgyy4d0dbxqz0', 6) AS "precision 6";
-[ RECORD 1 ]----------
precision 4 | POLYGON((-115.3125 36.03515625,-115.3125 36.2109375,-114.9609375 36.2109375,-114.9609375 36.03515625,-115.3125 36.03515625))
precision 5 | POLYGON((-115.1806640625 36.0791015625,-115.1806640625 36.123046875,-115.13671875 36.123046875,-115.13671875 36.0791015625,-115.1806640625 36.0791015625))
precision 6 | POLYGON((-115.1806640625 36.112060546875,-115.1806640625 36.1175537109375,-115.169677734375 36.1175537109375,-115.169677734375 36.112060546875,-115.1806640625 36.112060546875))
010300000001000000050000000000000000D45CC000000000800442400000000000D45CC000000000001B42400000000080BD5CC000000000001B42400000000080BD5CC000000000800442400000000000D45CC00000000080044240 | 010300000001000000050000000000000090CB5CC000000000200A42400000000090CB5CC000000000C00F424000000000C0C85CC000000000C00F424000000000C0C85CC000000000200A42400000000090CB5CC000000000200A4240 | 010300000001000000050000000000000090CB5CC000000000580E42400000000090CB5CC0000000000C0F424000000000DCCA5CC0000000000C0F424000000000DCCA5CC000000000580E42400000000090CB5CC000000000580E4240