I made a neat dynamic music system in unreal last lockdown and never posted it so here it is.
In normal game the choice in each column of music would be in relation to a certain in game element say party member, ability type etc and they would all combine to give the player a unique score but here I just use a debug menu to control it.
This uses the Quarts system to make sure the new audio is only starting or ending on the beginning of each bar.