Of course you need to grasp the basic of creating simple shapes in modeling software of your choice like arch, helix, etc. Once you get the basic done, the more procedural and mathematical in manipulating vertices, normals and UVs in Unreal Engine the better for your future career.
But no, an VFX artist, technical or not, would never be told to handle character or environment modeling, not from scratch at least. You might be asked to reduce the vertex count of a complex mesh thrown at you by your colleague or client which needs to be used in the particle effect, but that’s all.
As for Houdini, I recommend reading the reply of this thread.