So I was able to find a way to introduce a “persistent” z-offset for the Ender 3 V3 (plus or not plus).
First, the line:
z_offset: 0.100
in printer.cfg is completely ignored by the V3.
(some users found the same thing for the Hi printers: Z offset not saving - #16 by IgorA )
But the following line in [gcode_macro START_PRINT] in the file gcode_macro.cfg can do the trick:
SET_GCODE_OFFSET Z=0.100
This will shift the print head up by 0.1 mm for every print.
And this is almost slicer-independent.
One has to make sure that the slicer has the following line in the “Machine start G-code” section: START_PRINT
Actually Orca slicer comes with:
M140 S0
M104 S0
START_PRINT EXTRUDER_TEMP=[nozzle_temperature_initial_layer] BED_TEMP=[bed_temperature_initial_layer_single]