You might want to consider renaming your post title to be “open a specific page”.
From testing this out, it seems the page linking feature is meant for linking a PDF in Obsidian. Or embedding a PDF inside a note, and showing a specific page.
Judging from your syntax, you are attempting to create a hyperlink that opens a PDF in your system’s default PDF app? Is that right? And yeah that does not seem to work if you include a page number.
At the moment as the feature works (as far as I can tell) you can only “link” to a PDF page that’s inside your vault like this:
[[AnatomyandPhysiology-OP.pdf#page=100]]
![[AnatomyandPhysiology-OP.pdf#page=100]]