For a while after an update, it's normal for excessive battery draining, as your apps are adapting to the new update.
I've seen advice to use the features in the Samsung good guardians app (downloadable from Samsung app store) to decrease the affect on your phone's performance.
Edit: Since writing this my phone received the update, it was running slow etc., but I used the features of the good guardians app and within minutes it was back to a smooth running as if there was no update 😊