There is no “pressure” setting supposed to mimic real physics.
You can reduce flow by 2 manners : reducing volume of inflow or reducing its initial velocity.
I suggest to use both for a more realistic result.
You can use a disk as inflow and precise an high value for its Surface Emission under Flow source panel and decrease it to end simulation.
But mainly, you just have to animate Normal value under Initial Velocity panel.
I don’t understand why they did not consider the bug as a showstopper for 2.82 release.
Viscosity settings are working but Real World Size setting is not.
You have to scale down your simulation to fit into a domain that is 0.3 unit wide to actually obtain a simulation for a domain of 30 centimeters.
Otherwise, domain is too big to perceive a difference unless you guess how you should multiply viscosity presets to obtain correct result.
You can give insanely big values to viscosity settings, you should see a difference in a big domain.