How do you configure a pipeline and option to track only matching fields and set options to monitor updates or insertions exclusively?

How do you configure a pipeline to track only matching fields and set options to monitor updates or insertions exclusively?

Currently, my collection doesn’t have any pipeline or options, and it triggers every time there’s a change in the collection (updates, deletions, insertions). However, I need it to trigger only for fields with significant values.

let change_stream = state
    .db
    .posts_collection
    .watch(None, None)
    .await
    .map_err(|err| {
        eprintln!("Error creating change stream: {:?}", err);
        "Failed to create change stream".to_string()
    });

I need to set pipeline and opitons to trigger to the records that $match { “channel_id”: channel_id } But when I put this to the pipeline (covered in doc! ofc) it stops working for any operation
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