0402 means 0.4mm by 0.2 mm certainly smaller than 1mm !!
0201 means 0.2mm by 0.1mm... I have not seen smaller yet..
both of these are smaller than the "pico" size of 1mm by .5mm ... so that must be with the additional bulk of the wires, or more likely soldered to a small chip of circuit board.
I'm in Z scale, so this stuff is needed when you want to light up an F7 number board ha ha!
Greg