Manton says at the Help Center, Width and height of photos on Photos page?:

I’ve rolled out a change inspired by @kottkrig’s feedback. In the front matter, there is now a new “photos_with_metadata” with 3 fields: “url”, “width”, and “height”. I haven’t done much with this yet other than to confirm it’s working, but hopefully this opens up some more custom theme and plug-in possibilities.

11 June 2022