how to tranfer imovie project to ipad in macOS catalina ver 10.15

I am not aware of any way to transfer a Mac iMovie project to an iOS device like iPad.. iMovie for iOS is a different app than iMovie for Mac. iMovie for iOS has less features than iMovie for Mac. You can transfer an iOS iMovie project to iMovie for Mac, but not the other way around.

However, you can share out your iMovie for Mac project to your desktop as a movie, and use the Mail Drop app on your Mac and iPad to transfer the Movie to iPad.

Incidentally, when you mark your post as "Solved" when nobody has actually responded, then potential responders might not respond, believing that you have already solved your issue. Just a tip in the event that you make future posts.

-- Rich