Creo is not a basic CSG modeler. It is a B-REP parameterized procedural modeler. It has Merge to join surfaces into a water-tight surface which can be solidified. Depending on what support you want, it does support mixed mode - wireframe, surface, and solid geometry operations simultaneously in a single model. It does not support solid geometry cuts on wireframe and surface geometry, but it supports calculating intersecting geometry between the B-REP surfaces of the solid model and surface and wireframe geometry that can be used to perform some trimming operations.
Though this lists Creo as CSG, Constructive solid geometry - Wikipedia, the free encyclopedia, Creo doesn't support the feature operations typical of a CSG modeler, such as Intersect; which is the ability to create a solid that is the volume common between two other volumes. It only does Union and Subtract, though they are now lumped into Protrusion. CSG also tends not to have interdependent geometry. Traditional CSG features are independently placed and have independent.
What Creo does have are features such as Replace - where a face of a model can be replaced by a surface, which is definitely not a CSG operation.
