Congratulations on your new iPhone X! It's my understanding Messages has been using an unusually high amount of battery. I know battery life is extremely important. I'm happy to help.
To help resolve this issue, I recommend using the steps and tips in the links below:
About the battery usage on your iPhone, iPad, and iPod touch
Batteries - Maximizing Performance
If the issue persists, try restarting your iPhone. This can resolve many unexpected behaviors.
Restart your iPhone, iPad, or iPod touch
Please let us know if the behavior continues. Include any additional troubleshooting steps you may have tried.
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