If you believe your Apple iPhone may have been stolen or you don't want it falling into the wrong hands, you can remotely erase the information on it so no one else can access it. Google provides an app and website called Find My Device through which you can seek out your Android phone.
How to Find a Lost iPhone on iPad:
Before your device went missing, you should have set up the Find My (iPhone) feature. On iOS 13+, go to Settings > [Your name] > Find My > Find My iPhone. On an earlier operating system, navigate to Settings > [Your name] > iCloud > Find My iPhone.
Either way, make sure that Find My iPhone and Send Last Location are both turned on. The new Find My app comes with the added bonus of tracking your device's location even if it's offline. If you want this capability, make sure to turn on the switch next to Enable Offline Finding.
Find your iPhone on the Map:
Now, let's say your phone is lost. The first trick is to simply call it from another phone, but if that doesn't work, it's time to enlist the aid of another device. If you own an iPad running iPadOS, fire up the Find My app. In the lower-left corner, tap Devices. The app displays a list and a map showing the locations of any of your Apple devices that are currently turned on. If your device is running an older operating system, the Find My iPhone app will automatically show any registered devices on the map and in the list.
Select the iPhone Entry:
If your iPhone's location is visible, tap the icon on the map or the entry in the list. The app will then display a few options. Tap Play Sound and your iPhone will emit a pinging sonar noise to help you find it. Tap Directions within iPadOS and the app will give you directions to the lost device.
Mark Device as Lost:
If you can't find your phone, tap Mark as Lost in iPadOS (or Lost Mode in older versions). This mode lets you lock your phone so no one else can access it. If someone finds it, the device will display your contact information.
If you can't locate your phone and are concerned about it being accessed by the wrong person, you can erase all the information remotely. Once the iPhone has been marked as lost, an option to erase the data becomes available. Tap Erase This Device Erase iPhone on older versions to remove all personal information. The downside here is that an erased phone can no longer be tracked through this app, so only use this option if you have given up all hope of finding your device.
How to Find a Lost iPhone on Mac:
On a Mac with Catalina, you can use the Find My app to track down a missing iPhone. To get to the app, click Go > Applications > Find My in the top menu. In the Find My app, click the option for Devices. Click the entry for your iPhone from the list or select the icon on the map and click the Info button. From the Info menu, click the Play Sound button to play a pinging sound on your phone. Click the Directions button to view directions to your phone.
Select your iPhone on the Map:
At the map, click the heading for All Devices and choose the entry for your iPhone. Click the green dot for your iPhone. From the pop-up menu, you can now play a sound on your device to help locate it, put it in Lost Mode so no one else can access it, or erase all the data.