So I got this to work...

substringof('@{triggerBody()['text']}', Title)
Notice that the "search for this text" is before the variable that I'm searching in. I think I found that on another site.
I tried this...
contains(Title,'@{triggerBody()['text']}')
and I get this error...
The function operator 'contains' is not supported or its usage is invalid.
clientRequestId: a5bc9929-de80-4e9e-a10a-e060a2727bbe
serviceRequestId: a5bc9929-de80-4e9e-a10a-e060a2727bbe
I tried flipping them...
contains('@{triggerBody()['text']}',Title)
and the same error.
The person on this page is mentioning List Records in all their examples and not specifically querying a sharepoint list/document library, so I'm wondering if there are differences where SP won't accept some of those example Odata filters.