The "All Photos" album should be automatically sorted by date taken, at least, if the system version is Big Sur.
It is not possible to change the sort order of any album that Photos has automatically created for you. All predefined albums are having a fixed sort order, specific for the album. You can see the sort order, if you select the album in the sidebar and look at the menu "View > Sort". Your will see in Gray the fixed sort order for this album.
Only albums or smart albums you create for yourself can be sorted as you want them to be sorted. So she should create an own "My All Photos" as a smart album and then sort it.
- File > New smart album
- Set the rule to "date captured is before 1.1.4000".
This smart album should be showing all photos, provided, she does not take any photos with a capture date newer than the year 4000.