How to create 'image slideshows' with Photos (in large volumes, not one by one) with Ken Burns theme?

Hi friborg11,

Thanks for posting in Apple Support Communities.

We understand that you don't want to manually add your transitions to iMovie. Transitions can be added between clips automatically.

"Add transitions between Clips automatically

1. In the iMovie app  on your Mac, click Settings in the upper-right corner of timeline, and then select the “Automatic content” checkbox.
2. If you have applied a theme to your movie, iMovie inserts standard cross-dissolve transitions between clips, with occasional transitions based on the theme. Not every space between clips gets a transition.
3. iMovie also adds a theme-styled opening title over the first clip and an end title over the last.
4. To include only standard, non-themed transitions in your movie, click the Theme button, select No Theme, click Change, and then deselect the “Automatic content” checkbox.
5. Note: If you already have a theme applied to your movie and select No Theme, all theme elements are removed from the movie. For more information about themes, see Add or change a movie theme in iMovie on Mac."

You can find these steps and more in Add transitions in iMovie on Mac - Apple Support

Regards.