Most new phones do this for you as part of the set up. It will ask you what you are transferring from and prompt you to download the relevant app. 

iPhone to iPhone.

1. Turn on your new device and place it near your current device that's using iOS 12.4 or later or iPadOS 13.4. The Quick Start screen appears on your current device and offers the option of using your Apple ID to set up your new device. Make sure that it's the Apple ID that you want to use, then tap Continue. If you don't see the option to continue on your current device, make sure that Bluetooth is turned on.

2. Wait for an animation to appear on your new device. Hold your current device over the new device, then centre the animation in the viewfinder. Wait for a message that says Finish on New [Device]. If you can't use your current camera, tap Authenticate Manually, then follow the steps that appear. 

3. When asked, enter your current passcode on your new device.

4. Follow the instructions to set up Face ID or Touch ID on your new device

5. Tap Transfer from [Device] to begin transferring your data from your previous iPhone or iPad to your new device. If you're using the wired method, the transfer icon  indicates that your devices are connected. You can also choose whether to transfer some settings, such as Apple Pay and Siri, from your previous device to your new iPhone or iPad.

6. If you have an Apple Watch and you're setting up a new iPhone, you'll be asked if you'd like to transfer your Apple Watch data and settings. 

7. Keep your devices near each other and plugged in to power until the iPhone data migration process is complete. Transfer times can vary based on factors such as the connection type that you're using, network conditions, and the amount of data being transferred.