Create a slideshow project In the Photos app on your Mac, select the photos you want in your slideshow. Choose File Create Slideshow Photos. Click the Slideshow pop-up menu and choose New Slideshow. Type a slideshow name in the Slideshow Name field, then click OK. Edit Slideshow in Photos App on Mac in macOS Sierra. Launch Photos app and select the slideshow under Projects in the sidebar. To add more photos to a slideshow, click the, then select Add Photos. Now, choose the photos you wish to add, then click Add.
As far as I know, there are three ways (with Mac software) to make a slideshow: iPhoto, iMovie, and iDVD. The Ken Burns effect (the pan/zoom in/out) feature is not the best, so you will most likely not get a perfect result. I've made a fair number of slideshows and I've used a third party app for that for quite some time (because the built-in application didn't produce the quality I was looking for). I use Photo to Movie and it is absolutely great for special effects - it is not free though, but they have a free trial:
After I finish the slideshow, I export it at the highest quality settings and include it with video in iMovie or take it straight to iDVD to add a cool menu/theme.