Video Generation with Avtar, Avtar Placement and Background Image Effects

I want to create a video where an avatar appears first, and then after a second, it moves to the bottom corner. In the background, multiple images should appear with video effects.
This is achievable through the web interface by simply entering the prompt and property URL. However, I haven’t been able to achieve the same result using the API.
I’ve tried the following API endpoints:

https://api.heygen.com/v2/video/generate
https://api.heygen.com/v2/video/av4/generate

Could you please help me with this?