Euphorbia ammak, this may also be called the “Green Form” but then the real species E. ammak is a green species and the standard variegated E. ammak is more properly called E. ammak “Variegata” or better yet Euphorbia candelabrum erythreae variegata.
That’s kind of crazy that we would call one plant by another plant’s name. Why would we do that?
This one will get as tall as your ceiling, and no taller. That’s because you will have to prune it down when it gets that tall, and not later.