Here are examples from Iraq and Syria of what happens following different forms of Western intervention. It's crude, but hopefully it's food for thought.
1) Let the regime crush dissent without foreign interference. Casualties of the Hama massacre are in the low 10’s of thousands in a population of 9 million and prevented any serious armed uprisings for 30 years.
2) Provide rhetorical, but no material support, spurring the insurgency, but allowing the regime to crush the uprising. The 1991 Iraq uprisings killed in the low 100,000’s in a population of 17 million, and prevented a serious uprising for at least a decade (there were No Fly Zone’s during this time).
3) Establish no fly zones over insurgent territory. It’s hard to disentangle what was the effect of no fly zones and what was the effect of scenario 2 in 90’s Iraq.
4) Provide material support that doesn’t prove decisive, leading to a prolonged war of attrition. The current Syrian civil war has casualties in the mid-100’s of thousands in a population of 20 million. However airstrikes have saved the lives of Kurds and Yazidi’s from Isis.
5) Regime change via invasion, with too few troops, an ineffective counter insurgency strategy, political ineptitude and unable to provide amenities and security. Improve these things over time, by which time there’s been huge bloodshed. The Iraq invasion and it’s aftermath has possibly (POSSIBLY!) resulted in less per capita deaths per year than scenario 4, but it’s hard to tell. There’s been large-scale political violence even after the 2006-2008 civil war. However the counter insurgency that ended that conflict did prevent more wide scale bloodshed.
6) Regime change via a competent invasion and nation building. It hasn’t happened recently in an equivalent country, so we don’t know if it’s possible, let alone what the consequences would be.