We’re here at a certain point in time.
The past is over and therefore determined.
According to the theory of classical dynamics, the future is also determined, from the “initial conditions” (the present).
Unfortunately, even if it were, we don’t know the intial conditions precisely enough, and even if we did, we couldn’t solve the equations!
And anyway, the future is more like a quantum probability than a deterministic outcome.
That said, in answer to your question of when we cross the line to gov’t becoming tyranny, for the U.S. it’s been more like the frog in the pot with the temperature slowly rising.
It’s pretty hot now.
As they taught me in the military, you don’t have to respond to an illegal order, but if you self-determine it to be an illegal order, you had better be ready to fall on your sword over the repercussions. I agree that we have too many self-serving assholes in government, but I’m not ready to say that the pot is boiling.