Test NorthwindMiscellaneousQueryCosmosTest.OrderBy_ThenBy_Any does the following:

public virtual Task OrderBy_ThenBy_Any(bool async)
    => AssertAny(
        async,
        ss => ss.Set<Customer>().OrderBy(c => c.CustomerID).ThenBy(c => c.ContactName));

The top-level Any() means that we're meant to count the number of Customers in the database. We currently generate the following:

SELECT EXISTS (
    SELECT 1
    FROM root c
    WHERE (c["Discriminator"] = "Customer")) AS c

While this works in relational, Cosmos does not support uncorrelated subqueries; in other words, EXISTS can only work if the subquery source is an array property on the root JSON object (the Customer), but not on the Customers themselves.

We can probably make this work by translating to COUNT() > 0 instead. Or as @ajcvickers suggested, simply query the container with LIMIT 1 (and an empty projection). For example:

SELECT VALUE true FROM root c WHERE c.Id = 100 OFFSET 0 LIMIT 1