magento2 – Magento 2.3: How to configure fields to be used in Elasticsearch?

I need to configure the list of fields that are searched when you search in Magento. I am using Elasticsearch 7 as the engine. I need to stop it from searching by SKU and manufacturer, and add in a custom attribute to search by – either by changing what is indexed or changing what fields are searched.

I’m digging through all of the module-elasticsearch code, but it’s hard to find what I would need to override.