How do slave revolts work?

[c4liban]

So obviously when your public order hits -100 there will be a slave revolt. But what determines how big this army will be? In vanilla R2 I had slave armies that were almost a full stack,however in DeI the revolts I had so far had only 4-5 units,which can be easily defended by garrisons. So is it possible that there are bigger rebellion armies?I know they grow each turn,but when they are only 5 units at the start they are not even a threat,which makes the complete public order system redundant. Also what happens when there is already a rebellion and I hit -100 again? Will there be a second army?

[Dresden]

There are 2 type of revolts. Normal rebellions start out small and grow over time. Slave revolts start out at a full stack. From what I can tell I don't think that is moddable.