I have managed this with an ordinary red pelargonium, some years ago.
The trick is to take a cutting that is as straight as possible and once rooted keep pinching of the side shoots as they form.
Unfortunately it is very good at producing these side shoots and insists on showing you all year how good it is at its job!

I kept mine all year then when trying to repot it I snapped the stem and ended up with a tall bush!