There is still no automatic sorting of the People album. The People album is ordered by the date you added that person. The most recently added person will appear at the bottom of that album. There is no way to change this behaviour.
What I am doing is I grab the most recently added people at the bottom of the People album, where they are easy to find and drag them to the alphabetically correct place in the People album.
You may want to send a feature request to Apple to add an automatic sort option for named people to Photos. As it is, it is quite convenient for small Photos Libraries, but rather clumsy for large libraries with many named people. My library has currently 889 named people, and it is very difficult to drag the People albums across 30 pages of faces, without dropping them accidentally onto another album and merging the faces. The People album is really not suitable for a large Photos Library, as it currently is. The Catalina upgrade made it even worse, because the faces thumbnails are now larger and we have to drag an even longer distance to arrange the faces.
Here is a feedback form: Feedback - Photos - Apple