I think you mean to say, how much interference in the economy by the government produces a Pareto Optimum?
We call this a mixed economy. That is, a capitalist economy (which is the only economy possible long term), with social democratic redistribution via taxation. Under social democracy, property is owned by individuals, but proceeds are forcibly taken from those people for redistributive purposes. Social democracy is not socialism, since property is not owned by the state, and production is not organized by the state. (It cannot be, that’s why it isn’t).
In practice nearly all governments today practice social democracy. The difference is only in the level of corruption involved. Even very good people in the world (Hindus) have a tragically corrupt country.
Greece for example has both high corruption (bureaucratic) and high avoidance (personal). America has very sophisticated corruption (systemic), very little interpersonal bureaucratic corruption other than systemic corruption, and very little personal avoidance.