Does a new CKP relearn need to be relearn?

Yes. If you replace the crank sensor you need to do a relearn so that the ECU will know the signal strength and trigger level of the new part. Not hard to do, you use an OE level scan tool and go into special functions and the crankshaft relearn menu and follow the instructions.

Thank you very much.
But what does men OE level scan tool ? Please.

That would mean one that has bi-directional control, not one that just reads codes. You need one that can control the ECU for tests and resets. The first picture is a code reader, it basically can only read codes and limited live data. The second is a true scan tool. It can read error codes from all modules, live data from all modules and it can also activate test items and control items during testing. Say you need to test a headlight relay to tell if the switch is bad. The first one cannot do that. The scan tool can. They are generally what shops use to do full diagnostic testing.

Thank you very much.

You are welcome.