I think it's called "overdrive" pacing, and the article linked below provides a good explanation of how this works.

I have a pacemaker and have episodes of A-fib and/or SVT. Most of these episodes are short-lived, lasting for the most part less than one minute. I'd read of other folks whose pacemakers would raise their heart-rates enough to abort an A-fib episode, and I imagine this function is controlled by a setting that can be adjusted in the pacemaker. During my last visit to the pacemaker clinic, the tech informed me that this overdrive setting was active and working on my pacemaker. As she explained, when my heart goes into A-fib ( or A-flutter, which has happened before) probably also during SVT episodes which my cardiologist tells me go up to 170 BPM ( the A-fib is around 130), the pacemaker will pace up to a rate of 75 BPM which works well to abort the arrhythmic tachycardic episode, generally within less than one minute, seems to me. I'd suspected this might be occurring as I can sometimes feel the A-fib as it starts, but within a short time I can feel ( and hear with my pulsatile tinnitis) a strong steady heartbeat around 75 BPM take over which ends the A-fib. I suspect without that I'd have a lot more A-fib/flutter/SVTs.
https://scienceinsights.org/what-is-overdrive-pacing-for-fast-heart-rhythms/