In the latest WAB Query Widget (Product version: Online 7.1 / Kernel version: 2.12) under:
Edit > {Your Query} > Filters > Spatial Filters > Only return features that have a spatial relationship with features in another layer > Choose spatial relationship rules
I have only a single rule specified: "within"
When the end users execute this query, they are prompted with a full drop down menu with that single option.
It would be great if these single options would become hard-coded, or the creator is given an option to hide it all together.