$lexical in collections
This string is indexed and used for lexicographical matching and the lexical search component of hybrid search.
Only collections that have lexical enabled support the $lexical
field.
For more information, see Create a collection that supports lexicographical matching.
To be included in a hybrid search, a document must have both the $lexical
field and the $vector
field populated.
For examples of populating the $lexical
field, see Insert a document and Insert documents.