Some guides from Google , maybe they are good for you .
http://www.iphonetransferrecovery.com/tutorials/transfer-contacts-from-iphone-to-android.html
https://www.cnet.com/how-to/how-to-switch-from-iphone-to-android/
These third-party tools are not sure they can help us , transferring data from Android and iPhone is not as simple as transfer data from Android to Android