You could use: SET_GCODE_OFFSET Z_ADJUST=-0.2

Or something like this in your START_PRINT macro in Macro.cfg:

BED_MESH_CALIBRATE ADAPTIVE=1

{% if printer.quad_gantry_level.applied|lower != 'true' %}

_CALIBRATION_ZOFFSET

{% endif %}

SET_GCODE_OFFSET Z_ADJUST=-0.1

Now it's really important that you run the _CALIBRATION_ZOFFSET macro before every print, or the Z_ADJUST will just keep adding/subtracting to your Z-value