Short answer: the settings genuinely worth changing on a new iPhone are only a handful: confirm Optimized Battery Charging is on, tighten Background App Refresh and Location Services, trim notifications, and let auto-brightness and auto-lock work. The fifteen-item "must change" listicles mostly just cost you features.
More important than any of it is the order of operations: after the migration finishes, plug it in, join Wi-Fi and leave it overnight so the settling period can run (Apple's guidance is about 72 hours), and only then judge how warm or how efficient the phone is.
The first 72 hours: change nothing
In the first days after setup or a restore, the system is rebuilding search indexes, analysing photos, syncing iCloud and re-downloading and re-adapting apps. A body that is slightly warm and a battery that drains faster than usual are the expected settling behaviour. Turning features off during that window buys you no meaningful cooling or saving — the background jobs still have to run. Judge it by trend, the way New iPhone heat and drain in the first days describes.
The changes worth making
① Confirm Optimized Battery Charging is on. Under Settings → Battery → Battery Health & Charging. It learns your routine and slows charging past roughly 80%, so the battery spends less time sitting full under stress. This is built-in long-term care, and it needs no daily attention from you.
② Tighten Background App Refresh. Go to Settings → General → Background App Refresh and keep only chat and mail apps. Turning the rest off does not delay notifications — pushes travel over Apple's system-level push service, which is a separate mechanism. The trade-offs are in What is Background App Refresh?.
③ Rein in location access. In Settings → Privacy & Security → Location Services, switch apps that do not need live location to While Using. Location is often a bigger consumer than background refresh, especially for apps that keep requesting your position in the background.
④ Trim notifications. Notifications themselves are not expensive; lighting up the screen for each one is. Keep only the apps that genuinely need to interrupt you and let the rest deliver as a scheduled summary.
⑤ Let auto-brightness and auto-lock work. The display is one of the largest everyday consumers. Pinning brightness to maximum and never letting the screen sleep is an easy and easily forgotten way to burn battery.
⑥ Use Low Power Mode on demand, not permanently. Switch it on when the battery is low or you are away from a charger, and switch it off afterwards; leaving it on limits background activity and costs polish. The trade-offs are in Does Low Power Mode actually save battery?.
Two things that only need a glance
- Storage headroom. Check available space under
Settings → General → iPhone Storageand keep more than 10% free. A migration tends to carry the old phone's clutter across, so this is the cheapest moment to deal with it. - iCloud backup. Confirm a backup exists and know whether photos are set to Optimize iPhone Storage or to keep originals, because that choice decides how local space is used.
What not to do
- Do not install cleaner or battery-saver apps. iOS already manages storage and memory, and those tools cannot reach deeper — they either walk you through deleting things or sit in the background using power.
- Do not leave Low Power Mode on permanently. It suppresses the whole experience rather than the actual cause.
- Do not disable a pile of features on day one. Wait for the settling period to finish, then deal with a specific problem.
- Do not judge battery life or heat in the first days. That data is not representative of long-term behaviour.