Key Frames for Focal Depth in Video Animations

When setting up a video , can there be a way to control focal depth with key points ? I was trying to set up a video last week with some cool dynamic shots but once I got the animation how I liked it , it was very hard to get the video to focus on different parts at the times I wanted it to switch to focusing on another object . Would be way easier to make really nice animations with more focal depth control.