Can a CBE order holders use the title "sir" [closed]

No, one does not put a title before one's name, but letters afterwards.

If I were the holder of that prestigious appointment, I would use W. Vane CBE.

Moreover, it is for others to use a title, not me.
So I introduce myself, or sign off, as W. Vane, not Mr W. Vane.

But anyway, a CBE holder is not entitled to be called a Sir or a Dame.

Sir Elton John is called thus, because he has also been made a Knight Bachelor.