I searched the docs and there is no mention of order_by or sort (except default sort by _id).

https://docs.mongodb.com/mongoid/current/tutorials/mongoid-queries/#id1

Is it possible that Mongoid no longer supports order_by?

I found this documentation but not sure if is applicable:

https://www.rubydoc.info/github/mongoid/origin/Origin%2FOptional:order_by

Putting docs aside, it seems that order_by does not work.

ap Category.order_by(created_at: :asc).pluck(:name, :created_at)
[
{{ [0] [}}
{{ [0] "computers",}}
{{ [1] 2019-10-09 02:43:35 UTC}}
{{ ],}}
{{ [1] [}}
{{ [0] "cosmetics",}}
{{ [1] 2019-11-09 18:43:26 UTC}}
{{ ],}}
{{ [2] [}}
{{ [0] "electronics",}}
{{ [1] 2019-10-09 02:43:35 UTC}}
{{ ],}}