Reset ECU after new exhaust manifold/ O2 sensor?

Does the ECU need to be reset after swapping the cracked exhaust manifold and upstream O2 sensor?

I'd say it wouldn't hurt, but I've never had to. Are you having a specific symptom?

I do whenever I replace something like that.
Whether it is actually necessary or not I don't have a clue.
With my '00 I always follow that procedure.

https://www.cherokeeforum.com/f2/jeep-ecu-reset-procedure-46047/

I don't understand part of that procedure either.
Turn the headlights on and off?
But I do it anyway. LOL.

I was taught that when I worked for Chrysler that it was to discharge any capacitive charges in the system. We'd do that especially when replacing air bags. We'd go so far as to turn on the lights, honk the horn, hit the brakes... pretty much anything to get it all dissipated. It's the same idea for resetting the ECU since it turns any leftover "ones" in the computer to "zeros".

If the fuel trims are all messed up from a bad front O2 sensor, resetting the ECU will be the fastest way to getting the trims back in line.

If the CEL was light and you got codes related to the O2 sensor, then Yes. If not, then what Max said and Yes again.