Hey there Dew11,
Reliable battery life is pretty important when it comes to something as important as your iPhone, so let's team up and see if we can find out why the battery isn't lasting as long as expected.
It sounds like you have been taking good care to get the most out of your iPhone battery by adjusting settings to extend the life. Let's get to the heart of the matter and see what is actually using up the battery app-wise. About the battery usage on your iPhone, iPad, and iPod touch has some great steps to take to see what is actually using up your battery and you can get a list of apps from the last 24 hours and up to the last 10 days, so you can see if there are any patterns.
You can also check your battery health from here, which likely won't be an issue for an iPhone as new as yours, but it's worth a look if you're already here. If you see any apps that are behaving out of the ordinary or are using up way more battery than expected, you might want to update them or reinstall them. Don't let the name of the bottom link confuse you. It's a great tool as step 4 will tell us how to reinstall problem apps.
Update apps or use automatic downloads
If an app unexpectedly quits, stops responding, or won’t open
Let me know how that goes.
Have a great day.