How to select photos from an album using smart ablum like rules
I think out a way to do it:

Create a smart album by using two rules: album is 'old iPhone' and photo isn't screenshot.
Then create a regular album and move all images in the above album to it. In this way I created a regular album containing only camera pictures from 'old iPhone'.
Use similar steps to create a regular album containing only screenshots from 'old iPhone'.
Remove 'old iPhone' album.

The smart album created in step 1 is a temporary album. I need to introduce it because, as far as I can tell, that's the only way to select files using rules rather than manually. On the other hand, I can't just use it for final result, because if I understand it correctly, after the 'old iPhone' album is deleted, it will contain nothing.
I haven't actually tried the above approach because this is my first day using the Photo app on macOS and I'd like to see if there is any better approach. The above approach involves multiple steps and it would be good if there is some way to combine these steps.