Transfer Whatsapp chat History from Android to iPhone
There are two scenarios.
- WhatsApp Chat is on the Android Device
- WhatsApp Chat is backed up on Cloud Drives

WhatsApp Chat is on the Android Device:
- Move to iOS only transfers WhatsApp chats that are locally present on the Android device.
- If the chats exist only in Google Drive and are not restored onto the Android phone first, Move to iOS cannot see or move them.
If all your WhatsApp chats are on the Android Device and have not taken a chat backup then... Please use --> Move from Android to iPhone, iPad, or iPod touch - Apple ... Select the WhatsApp App while selecting which data you want to transfer from an Android device to iOS.

WhatsApp Chat is backed up on Cloud Drives
- Google Drive backups cannot be read or imported by iOS.
- Android → Google Drive and iOS → iCloud are two separate worlds that do not speak to each other. No official bridge exists.
- iOS cannot restore an Android WhatsApp backup directly.
- A Google Drive backup cannot be signed into or restored on an iPhone.
WhatsApp Chat backed up on any Cloud Drive may not get fetched. The Move process cannot extract data from Google Drive or any other Drive where the chat backups are stored using an Android device; I presume iCloud Drive is not one of them. My experience says you can't transfer the WhatsApp Backup which was done using an Android because on Android, WhatsApp chat history is not stored on iCloud, on iOS it is.
That may be possible with third-party software. Warning!; WhatsApp data through third-party software has the risk of data being compromised. Because the data will be churned through third-party servers, which may or may not be encrypted. Be judicious while selecting the software and taking this call.

If WhatsApp Chat backup has been enabled on your Android device and some chats are missing, please contact the app developer via the --> App Support or WhatsApp FAQ , Or Restoring your chat history - WhatsApp FAQ or Contact WhatsApp