That depends on what you deliver via the Deliver Now button.
From Fiverr’s Terms of Service:
“Sellers must deliver completed files and/or proof of work using the Deliver Work button (located on the Order page) according to the service that was purchased and advertised on their Gig.”
“Using the “Deliver Work” button when an order was not fulfilled may result in a cancellation of that order after review, affect the seller’s rating and result in a warning to seller.”
If you deliver completed files, the order gets marked as complete, and then the buyer asks for changes via inbox and you do those changes, it should be fine.