Assuming you have a 6mm2 circuit with a 30 or 32 amp protective device, you would run 6mm2 to the first socket, then from there 2.5mm2 to the second socket.
OR, 6mm2 to a 30 amp junction box, and one 2.5mm2 from jb to first socket,
another 2.5mm2 from jb to second socket.
OR just do all in...