What is the optimal database structure for rating?

Question

firebase

I use the firebase Cloud Firestore database, I make a user rating system:
each user has points (a rating is built on them). It is necessary to display to the user where he is.

The following scheme immediately comes to mind:
rating -> userID -> score: N
then get the entire list, sort by the score field, find the desired userID and show where it is.
But it does not sound optimal - if there are tens of thousands of users, then such a search will not be the fastest. Can you please suggest how else can it be implemented?