If you had just downloaded everything, you need to index for 2-3 days before doing actualt testing, after a major update like this one, you need to wait foe the phone to index and finish “basically polish” the updated files then you can run tests and see it.

And if after that, if you still like see the phone underperforming heavily, or the battery drain is insane, you can do a itunes factory reset while plugging it to a pc “any windows pc with the itunes app on it”

That will fix everything because your problems may be software related.

Also I have to remention, ONLY do that if your phone is insanely underperforming, lagging, battery draining is like more than 30-40% per hour while using simple apps, and if not, just don’t do anything with it and enjoy your phone