I’ve now found the relevant section of the documentation: https://steinberg.help/dorico_elements/v3/en/dorico/topics/play_mode/play_mode_tempo_mode_changing_t.html
Also, I think the forum thread I had discovered was actually about a slightly different feature request - the ability to easily speed up or slow down playback, in a relative fashion. (i.e, 20% faster, 30% slower, etc etc). So, this feature would presumably honour “follow tempo mode” as well.
I’m very pleased with the existing functionality for now, and am relieved it’s there. I simply had failed to find it in the doco. (I was searching more for “metronome” topics, than “tempo” topics)