Options for displaying PDFs when using Image Server

We’re looking for help to display PDFs in either the native browser PDF viewer or another option that will let users browse the entire document.

Our current problem is that only a tile of the first page of the PDF is loading within the OpenSeadragon viewer (when the global/site settings for Image Server are set to tile). If we adjust the global/site settings for image server to ‘original’, then it works, but we don’t want to apply this across the board to large TIFF images.

Is there a way to treat PDFs separately from other image files, or any other solutions?