Search Notes With Omnisearch
Introduced in v1.2.0.

This action queries the Omnisearch community plugin and returns the file paths of the notes found. It does not return the notes themselves, just their paths.
Use the "Get Note" action with the returned file paths to get the actual note contents.
The search query is passed to Omnisearch as-is, so any search terms available in Omnisearch can be used. See the Omnisearch docs for details.
Please note: Omnisearch is a community plugin and not installed by default. It's really good, though, so I recommend giving it a try!
Examples
Most of the time you would use this action to get a list of search results (their file paths), then loop over the results list using the built-in "Repeat With" block. If you want to retrieve the details of the notes, you would use a "Get Note" action and use the loop variable Repeat Item
as the argument for the "File Path or Name" parameter.

If you want to filter the list by folders etc., I recommend using the "Filter List" action from Sindre Sorhus's excellent Actions app (no relation) or a built-in "Repeat With" loop with a contained "If" action.