Is there a D&D 5e equivalent of the e6 variant style?

Now that 5e’s been out for a few years, has anyone found a point past which characters have a significant jump in power and developed a set of rules for capping levels below that, similar to the “E6” system in 3.x?

If there’s not a generally accepted system, has anyone created and used a set of rules that accomplish the goal of capping play at a modest power level, where PC’s can’t topple kingdoms by themselves? Specifically, I have a large city on the verge of a peasant uprising, where I want the players to be able to influence the outcome one way or the other by strategically picking battles, running supplies, advising leaders of different factions, etc., but not by just blasting whoever they want to lose.