G28 & G30 can be used for that.
Can of worms following…G55-G59 WCS can be used.
Untested, but tool length offsets are temporary (in grbl) and are not stored in the controller’s memory across power cycles or resets. Not sure if CM is storing something, though.
Anyone near a machine today able to catch the log output on pressing “clear offsets”? I’d assume just a G10L2X0Y0Z0