Make sure that the iCloud Photos option is checked. Here's how to enable the iCloud Photo Library. ICloud Photo Library is probably the easiest way to keep your photos on Mac and iPhone in sync, but you do need a newer Mac that can get the Photos app on it (macOS Yosemite and later).
Otherwise, you'll want to consider using the iOS Files app.
These will all appear fine in the Photos app, but you won't be able to tell what format they are on the surface - it will all appear rather seamless. The Photos app on iPhone and iPad can display several different types of file formats without issue. What content can I view on my iPhone or iPad?
