Hi @rnfr247 ,
Much of this will depend on what you want to do with the mesh. Converting this to a high poly form and working solely at high resolution may be possible. Converting this to editable low poly geometry may be beyond reach.
Unfortunately, this model has already been decimated or highly optimized for export, and in the case of a hard surface model like this there is no simple way back to a more editable state. It contains a mix of subtle curves and hard angles, so you can’t just disable subdivision smoothing.
This asset is designed to be used as-is, not to be easy for further editing. If further editing is desired, try to find models still in quad topology form before they have been decimated or optimized for export.
Even if you had access to that geometry, the detail here is probably too fine to survive a ZRemesher pass. Dynamesh is out of the question. Manual retopology is possible, but certainly won’t be fun.
The problem is that the long, highly stretched triangular polygons don’t really provide enough surface information to get good results from ZRemesher. They also make manipulating the topology very difficult. Because there is no polygroup/crease information you won’t be able to subdivide it and maintain the shape. Those triangular polygons would not subdivide well in any case.
To convert this to editable low poly geometry would require you to manually assign either edge creasing to all hard edges, or distinct, cleanly defined polygrouping to all planar surfaces that are separated by a hard edge. Both of these can be used to instruct ZRemesher to place an edge at that location, which can then be creased to stay crisp when subdividing.
It is my opinion based on the screenshot that much of that shallow recessed detail will not survive a Zremesher pass no matter what you do.
However! Let’s take a look at what you want to do:
That can be done as long as you get the model to high enough resolution to maintain its shape by virtue of the sheer number of points on the surface. You may be able to use the Tessimate feature for this. Go to Tool> Geometry> Tessimate. Disable the “Decimate” option so that only Tesselate is active and reduce the poly size as far as you can, or to the desired level.
This may redistribute the points over the surface in dense enough fashion to be able to sculpt on with alpha brushes , Spotlight, or Noisemaker. It may even keep most of the detail. Once the points have been redistributed over the surface of the model you may then be able to subdivide it one or two more times to increase the resolution even further. Since the hard edges in this case are being maintained by virtue of the dense geometry you’re starting with, it should be able to be subdivided without “melting”.
Then you are in a high resolution sculpting scenario. Sculpting fine surface detail should not be a problem. You can then simply Decimate for export again if your end goal is print.
If however you are looking to convert that model back to low poly for the purpose of unwrapping for UV textures or displacement, you will face the same challenges. Hard surface geometry has special concerns, and typically requires some forethought if you are looking at a high res to low res workflow.
I’m sorry I couldn’t be more helpful 
