The SPU Library has books and ebooks with collections of monologues. Look for the ones that take the monologues from actual plays. These are more authentic and have context to help you understand how to produce the monologue.
To find these resources use the SPU Library Catalog. Use the term "monologues" and then look for the ebook limit on the left side if you only want an online source.
For print books that you find in the catalog, you can request Contactless Pickup
Below is a list of some recent ebook collections of monologues available through the SPU Library: