For example, one existing condition in the US is the fentanyl crisis. The US government has chosen to respond to this existing condition by continuing the criminalization of drug abuse and using the crisis as justification for imperialism in Venezuela. The US could have chosen to respond by funding addiction treatment centers and decriminalizing drug abuse.

Flip it around. The US Empire didn't randomly choose to attack Venezuela, the imperialist system itself found justification for doing so. The mode of production takes priority over the what actions a system takes, its internal contradictions are what drives its change. The US Empire is in a state of decline, and thus needs to re-exert itself millitarily. The conditions are that imperialism is weakening, the outcome is the violent re-assertion of control. Had imperialism been working fine and Venezuela colonized by the US, it would not be attacking Venezuela right now, but the capacity for doing so already exists.

Another example, an existing condition in China was population growing faster than their economy could keep up (ostensibly). China chose to respond with a one-child policy, restricting reproductive freedom. China could have chosen to respond by encouraging contraception and creating financial incentives and disincentives.

In 1954, condoms and cervical caps were already promoted over abortions for family planning. They continued to promote birth control, in the early 1970s they sent "barefoot doctors" to the rural areas where birth rates were higher to teach about contraceptives and provide abortions if needed. It wasn't until 1979, 25 years after they started promoting modern methods of birth control and incentives for lowering birth rates that they implemented the One Child Policy, exempting ethnic minorities. It wasn't the first, second, third, fourth, or fifth tactic, but one finally employed after 25 years, over a decade and a half from the baby boom in the 60s. The state responded to crisis in increasing measure because simply promoting awareness of birth control and providing it for free did not work at the rates needed.

What you suggest is political determinism, implying that there is only one way that a state can respond to existing conditions, when in fact there is a vast range of possibility.

Not quite. My point isn't that choice doesn't exist, but that the extent to which measures are employed and the types of measures employed depends on the class character of the state and the existing material conditions the state finds itself in. Modern Germany doesn't have a lesser potential for authority than Nazi Germany, it just hasn't had the need to thanks to benefiting from decades of imperialism. Now that imperialism is crumbling, it's trending to the far-right again. This isn't because of any choice for authority, but the state responding to real conditions.