Add the Ken Burns effect in iMovie on Mac
You can add the Ken Burns effect to a video clip or photo to make the camera appear to zoom in to or out of the clip or photo.
In the iMovie app on your Mac, select a clip or photo in the timeline.
To show the cropping controls, click the Cropping button.
Click the Ken Burns button.
Two frames, labeled Start and End, appear over the clip in the viewer.
Do any of the following:
Set the crop at the beginning of the clip: Select the Start frame, and then drag and resize it until the beginning of the clip is framed the way you want.
Set the crop at the end of the clip: Select the End frame, and then drag and resize it until the end of the clip is framed the way you want.
To apply the change, click the Apply button in the cropping controls.
When the clip is played back, it’s cropped at the beginning of the shot as set by the Start frame, and appears to zoom in or out based on how the End frame is cropped.
To reset all crop and rotation adjustments, click the Reset button.