Altium: problems with generation 3D body with IPC component wizard
The STEP model created by the Alitum Wizard is not editable, at least inside Altium. Actually you can't modify any STEP model in Altium.

I suppose you could go around this doing this:


Placing the footprint in a PCB
Exporting the PCB into a STEP model
Modifing the STEP model in a CAD tool such as Solidworks.


It doesn't seem worthy at all.

I would suggest one of the next options:


Searching on the manufacturer website. Some of them provide the 3D model, mainly for connectors.
Searching for the STEP model in these repositories 3D content or TraceParts or https://b2b.partcommunity.com/3d-cad-models/ .
Creating the 3D model in a CAD tool by yourself.


Failing all this, you can create a basic 3D model in Altium extruding basic shapes.