How do I change the order of photos in albums to match the main library on iPhone?

Although, nothing much has changed except to give you more options. New photos, by default, add to the bottom. You can change the sort order by using the up/down arrow.

Filter and sort photos and videos in albums on iPhone - Apple Support

Hit select and hold photos down and u can edit them sorta similar to home screen apps

When you first open Photos, the newest pictures appear right in the middle of the screen,

which seems pretty reasonable, to me. Also, you can see recent albums. You may remember that before, you had to hit buttons to see one or the other, whereas now you see both and, rather than using a button to see more, you just scroll up for the Library or down for the albums.

As muguy said, you can now sort the Library view

to see either the newest pictures taken, or the newest pictures added.

And with "View Options"

you can also restrict the view in more ways, so you see only Favorites, for instance, or only pictures you haven't yet put in albums, and so on. There's way more options, now.