In desktop ArcGIS, you can configure hyperlinks to open to a specific page in a multi-page pdf, if your attribute data has the page number. In ArcGIS online if you have a multi-page PDF stored as a feature attachment, and your attribute table contains page numbers for each point/line/polygon in the map, can you create a way to click on the feature attachment and have it open to page 52 of 144 for example?
I have an engineering record/as-build map viewer where the extent of each sheet from a plan set is graphically drawn as a rectangle on the map. The PDF page number is stored as an attribute, and the multi-page pdf is stored as a feature attachment. But it is cumbersome to open a 200 page PDF attachment and scroll to page 147. I don't have an internal web server or I could just store them as a pdf page open url. https://helpx.adobe.com/acrobat/kb/link-html-pdf-page-acrobat.html