Opening PDFs consistently across platforms

I have a page of <a> links that all open PDF documents. On web browsers, these all have the target="_blank" so they open in a new tab in the default PDF viewer. This works on Android too (they open in whatever PDF viewer app is defined in settings) however on iOS they open directly in my app with no back button or other controls to get out of the PDF view without closing and re-opening the app.

I’ve seen a few posts online that recommend setting target="_system" to specify opening in the system browser which works as expected on Android and normal browsers, but the link does nothing on iOS.

Any suggestions?