It does not - and worse, if you do a G29 it will almost certainly crash the tool into the bed. The only way to trigger an autocalibration via gcode is detailed here: How to do a larger than 3 x 3 matrix level
MEASURE_BACKLASH_WHEN_PROBING is not defined in this firmware, and running G29 will not do anything productive on this machine, unfortunately.
However, it’s fairly easy to measure Z backlash manually, just by feel with the card, and by setting Luban Z jogs to a custom value of 0.01mm.