By default, iMovie for iPhone inserts a fade (also known as a fade) between all video clips. The timeline for your movie project is an effect that gradually transitions from the end of a clip to the beginning of another clip. However, IMovie will not add any initial transitions or the last video clip to your first video clip. That does not mean that you can not.
While movies may start or end abruptly without transition, many appear from black to the first frame of the video and black in the last frame. It's similar to a crossfade, but instead of switching between two different video clips, it's just a transition from a clip to a blank screen (usually black).
With Apple's iMovie, you can easily add these start and end transitions to your movie project. Unlike other video editors, such as Adobe Premiere Clip, you can also add overlays between video clips. These transitions hide the first clip in black or white and then blend in from black or white to the next clip in the timeline.
How to Add Fade Ins & Fade Outs to Your Movie Project
Let's discuss the simplest option: adding a fade in black or fading out to black for your entire movie project. In your movie project, tap the gear, and then choose either Show Black or Hide to Black. You can also select both if you want. Tap Done to complete the process.
Below are some examples of a short film project without fades and fades (left side) and applied (right side). Unfortunately, the effect is fast, and there is no way to control the speed of the fade transition, as in apps such as Videoleap.