Let’s imagine that you quickly created required mesh with Boolean modifiers (or with any other way, which produces bad topology) and now you want to sculpt additional details and make a good high poly mesh.
First what you need is to increase polycount for your low poly model. But with bad topology, it’s really hard to get a nice result with subdiv modifier. In this quick tip, I will show you a quick way to overcome such issue.
Let’s add bevel modifier with 6 segments and set the profile to 0.9. You can use any suitable limit method for bevels. Then add subdiv modifier with 3 levels and you will probably see a lot of artifacts over your mesh if it has a bad topology. Triangulate big ngons (especially around circle holes). Don’t use triangulate modifier for that, use ctrl-t hotkey.
Then duplicate your mesh and apply all modifiers (to speed up further calculations), hide original mesh and add remesh and corrective smooth modifiers. Firstly, set parameters for corrective smooth modifier like in the image (only smooth and pin boundaries set to true, factor = 1, repeat = 40). Then for remesh modifier (Smooth mode, Smooth shading, Octree depth = 10). Octree depth = 10 is enough for most cases, but you can use bigger values (like 11 or 12) if you need more polygons. And voila, now you have a good high-poly base mesh for sculpting additional details, which you can use for baking normals (or any other maps) for a low poly model.