I'm looking for a course search plugin that would restrict only to the users enrolled courses. Does anyone know of an existing plugin that would do this?
You can enable the already existing Global search function to do this. This automatically limits search results for normal (non Admin or Manager) users to only those courses they are enrolled in. The Simple search will do this just by turning it on. More here at https://docs.moodle.org/38/en/Global_search and https://docs.moodle.org/38/en/Global_search_block.