DocumentDB how to reduce RU for request

In my collection, I write a query and get 500 records, in the event that I have specified a section key that consumes a high RU, and if I do not specify a section key, I will show REQUEST CHARGE 0 RU's

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What are the steps to be taken to minimize RU rights. For each query, when the query filters a large amount of data with multiple conditions and receives a large amount of data.