I remember achieving this "auto anchor to transient" thing after applying Strip silence to a region (or remove silence, don't remember exactly the name of the function)
After applying it, the resulting new regions were anchored to the highest transient, and it was very convenient for video or tempo sync, but now it does not happen anymore, I don't know if it is because of an update or because I changed some option without knowing. But would love to have it back if anyone knows how.