You put your cursor over the post number/total posts thingy on the right. Cursor changes to double-arrow-headed one and you can then hold the left mouse button down and drag downwards (or upwards).
And there was me clicking the page number at the bottom right of the thread and typing “999” in the Type-in-the-Page-You-Want-to-Go-to box that comes up.
Or, for some particularly busy threads , typing in 9999.
The system will then take you aa near as it can get to 999 or 9999. Which may only be page 16, if that’s the current last one.
I always do the first of what @Stella suggested - i.e. clicking on the 2m or 12h or whatever a bit below the timing of the first post (on the right). At the moment (just about to change) it says 12h. When I’ve posted this it will start by saying 1m and then rack up…
I didn’t know about the double arrow, or the page number possibility so that’s good to add to the list!