Lexile is a score used to match reading ability of a person with the reading level of a book. Lexile is added to many newer J and YA books, it may be seen in the Library catalog, (under the tag = "Audience") and can be searched in our keyword search, simply search lexile 300 (or whatever Lexile you are looking for) in the default search box.
You can also look for more Lexile based searching in the NoveList Database, see: https://www.tolibrary.org/virtual-library/reading-suggestions and scroll down to see NoveList K-8 Plus. In "Advanced Search" you can see the options to select a specific Lexile, or a Lexile range. You can also use this feature to search by Grade Level or by Accelerated Reader Interest Level.