multiselection

The application must be designed to permit non-contiguous text selection. Apple's discontinued Pages '09 v4.3 (even in High Sierra), and TextEdit have this feature, but Pages v5/v6 do not. Outside of the respective application itself, there is no operating system override to enable non-contiguous text selection in an Application that wasn't originally designed for that purpose.

How are you currently trying to do this? You know to use COMMAND to make non-contiguous selections? What word processor are you using? Mac keyboard shortcuts.

Just to add, if you are trying to choose multiple selections online, Firefox allows that and you can also use it to open a PDF and make multiple selections.