Protect your privacy, improve battery life, and get the most out of your iPhone
Access the System Services by opening Settings from the Home Screen, tap on Privacy then Location Services, scroll down and select System Services
Apple Pay Merchant Identification This setting is tied to your physical Apple Card. Unless you have a physical Apple Card, there isn't a reason to have this enabled.
Cell Network Search This sends data to Apple to let Apple know which cell towers are being used. It's safe to turn this off.
Compass Calibration This is specifically for the compass app. If you use Google or Apple Maps, I recommend keeping this on.
Emergency Calls & SOS Keep this enabled.
Find My iPhone Keep this enabled incase you lose your iPhone!
HomeKit If you don't use HomeKit, you can freely disable this.
Location-Based Alerts I personally use location based notficiations in HiFutureSelf "When I get to the store remind me to buy Avocados". Also the Wallet app brings up my boarding pass when I get to the airport. Your call on this.
Location-Based Apple Ads No, thank you.
Location-Based Suggestions Nope.
Motion Calibration & Distance Mostly used by fitness apps. It's safe to disable. If you find your fitness apps are not functioning correctly, you can re-enabled it later.
Setting Time Zone This setting automatically adjusts your timezone based on your location. If you disable it, you'll have to adjust it yourself when you arrive to a new timezone. (I pesonally have this disabled)
Share My Location Unfortunately friends get lost. If you have friends, and need to share your location from time-to-time to make sure you find eachother... you'll need this enabled.
System Customization Your iPhone will customize behavior based on your current location. No thanks!
Wi-Fi Calling WiFi calling uses your WiFi instead of your network provider to make calls. Some cell providers like T-Mobile support this. If you use Wi-Fi Calling, you'll need this enabled.
Wi-Fi Networking & Bluetooth This is just like the Cell Network Search setting, but for Wi-Fi. You can safely disable it.
Significant Locations As Apple phrases it: "Allow your iPhone to learn places significant to you in order to provide useful location-related information". NO!
iPhone Analytics No.
Popular Near Me I'm not popular and I don't care.
Routing & Traffic Apple monitors your speed and location and uses that to inform the traffic level in Apple Maps. Nope.
Status Bar Icon YES. This will show the location icon in the status bar anytime your location is pinged.
Read about App Location Privacy Settings