I would say that the institutions of society as well as the general impulsive fear of death (the self-preservation mechanism) is
influential and typically enough to keep people from even considering death as an option (see: Becker). But it is not in the sense
absolutely coercive as there are methods to get around these blocks if one thinks their life is truly not worth living. They might not be perfectly clean or easy but they are still viable options that can, and in fact do, work.
I would hesitate at your (seemingly) assumption that the only reason people continue to live is out of instinct. I would say that those who have not analyzed their lives sufficiently do indeed continue to live out of instinct and habit. But there are people, more rare though, that continue to live out of spite and out of rebellion (re Camus) or because they feel they have an overarching purpose behind their lives.
If you would argue that these too are indeed merely psychological walls to keep us entrapped, then I would hesitate and ask you if you believe that a person
ought to end their lives. This does seem to be the deciding factor in whether or not instincts and society are indeed coercive. Because if there is no impetus to end one's life, then clearly this means that the influential forces of instinct and society have no weight as they aren't contributing to keeping you from ending your life.
Additionally, I would also argue that these instincts are not necessarily bad in themselves. I believe Becker himself argued that one thing humans need are better, sturdier psychological walls in which we can live our lives in peace without the looming threat of death always on our shoulders. This goes back to what I was saying about the normativity of death. If these psychological walls not only shield us from thinking about death but also give us bountiful purpose and meaning from culture, art, music, philosophy, scientific inquiry, relationships, etc, then surely there is no inherent problem with the implementation of these walls. They may distract us, sure, but they work. Even Zapffe knew that there was a fourth option for those who cannot seem to attach, distract, or isolate themselves: sublimation.
And so we can live Absurdly and change these
"coercive" "influential" modes of thinking into something that we simply accept and move on. We can treat it as one would treat the ability to fly: ultimately not possible for a naked man but given his intellect and ability to use tools, actually possible if he does so desire. It only seems coercive if you have never tried or have tried and failed due to poor planning, but it's not coercive in the way a jail cell is. The ones who have succeeded are proof that our instincts are only "coercive" insofar as we allow them to be. And sometimes if we give in to our instincts, they can lead to some great things (mentioned above) that doesn't make it seem like it is "coercion".
So the question here is whether or not it is in the best interests of an agent to die, and if so, then the instincts and societal institutions do indeed act as some kind of barrier, obstacle, or Catch-22 that a person must overcome in order to perish. But let us not forget that the existence of a barrier does not prevent one from breaching it, nor does it prevent one from living a life peacefully and in harmony.