Good reasons to use displacement maps are very rare, compared to (a) using real geometry, or (b) using a normal map. It’s also very common to confuse displacement maps, bump maps, and normal maps — can you share the model and the texture you are talking about? If you don’t have a particular model in mind, then you should definitely not be thinking about displacement maps yet. Use real geometry if it’s performant, and bake the details of that geometry to a normal map when performance isn’t good enough without it.
As a rule of thumb, if you have more than 100,000 vertices in the scene, you should think about using a normal map to reduce that.