How can i make A320neo flybywire liveries?

Not sure I understand the question. Do you want to make "default A320NEO into FBW" or vice versa?

No, I think he wants to know how to make liveries for the A32NX. Have a look at this: https://docs.flybywiresim.com/dev-corner/texture-changes/ and this https://docs.flybywiresim.com/fbw-a32nx/liveries/