I’m here again, with some data.
Now the current in system off is around 246uA, better than before but not yet what I need.
Just to summarize my system off setup, now I put the onboard flash in deep sleep mode, no output is active, no serial, DC/DC is ON , the gyroscope is disabled, the accelerometer is active in low power (ODR 26hz), just to use the embedded tilt function that I use to generate the interrupt on int1 , configured as wakeup source with the statement "pinMode(PIN_LSM6DS3TR_C_INT1, INPUT_PULLDOWN_SENSE); ".
There is something else I can do?