Sensor Offset Question

How far from center of gravity does it become relevant to set the INS Offset? For GPS, I’ve set -7cm on the Y axis for the sake of RTK accuracy. IMU’s are 3cm forward on the X but I haven’t made those settings change yet.

Not very critical unless you’ve got a very large aircraft, maybe you’d do it if the flightcontroller was 20cm or more from the centre - bit of a guess though.

My flight controller is 33cm backwards from C.G point.i haven’t configured the INS offset but RTK GPS for Yaw measured with respect to C.G point.
I have to set FC offset too?

You set offset on all accelerometers, it should be INS or IMU something X Y Z

INS_POSx_X
INS_POSx_Y
INS_POSx_Z
Do you refer with respect to C.G of the frame.

Yes, though any fixed point near actual CoM will be good enough. For copters frame center should be good enough.