What happens if your body doesn't fight a cold virus

Its my understanding that a lot of the symptoms of the common cold are due to your immune system fighting against the virus, not the virus itself

What happens if your body doesn’t fight the cold virus (which I believe are mostly rhinoviruses)? How badly does it spread and how far does it go in your body?

Rhinoviruses can and will cause pneumonia if they get the chance. It seems that the majority of pneumonia cases in immunocompromised patients are rhinoviruses, which is the reverse of healthy people. Probably because the virus is so common it is just the most likely to hit first if you are vulnerable to any and all viruses, whereas normally a healthy person will wipe out most infections before they progress.

So absent any immune response one suspects that the simple rhinovirus is quite capable of killing you. If you never clear the infection the probability likely rises to a certainty.

The dark days of HIV probably give good guidance.

I’m also thinking of a “bubble boy” situation, where an otherwise minor illness can be deadly.

AIUI, just any pathogen disease that runs unchecked throughout your body will by default be eventually fatal.

Is the mechanism of damage for an unchecked virus that it enters cells, replicates out of control, basically, and the cell ruptures? If that’s not it, what is the mechanism of damage?

Short version:

You will suffocate to death as your lungs fill with fluid.