Use the Move to iOS app during iPhone setup
On Android, install Move to iOS from Google Play
On iPhone, choose Move Data from Android
Connect both devices to Wi-Fi and keep them plugged in
Enter the code shown on iPhone into the Android app
Select Contacts on Android
Tap Continue and wait for transfer to finish
If the iPhone is already set up, erase it and set it up again to use Move to iOS
Sync Android contacts to your Google account
On iPhone, add the same Google account in Settings
Turn on Contacts sync for the Google account
Export contacts from Android as a VCF file
Send the VCF file to your iPhone by email or cloud storage
Open the VCF file on iPhone and import the contacts
Use a SIM card only if your contacts are stored on the SIM
Check that all contacts appear in the iPhone Contacts app