The Explore Editions & Formats sections use, by default, the Library relevancy algorithm for sorting the results. The library sort takes several details into account. Highest on the list is whether the library owns the item, but then it also boosts by date and the number of worldwide holdings.
A detailed summary of algorithm features can be viewed on this Community Center Post:
https://www.oclc.org/community/discovery/search-platform.en.html