where does the helper sleep in a 2 bedder ?

hi - i’ve been struggling with this question because, if you are in a 2 bedder condo which doesn’t have a yard or utility room (say 700 sq ft size) and there are two adults and a child - where on earth do you house the helper ? it seems like the only option is to bunk in with the child (?) but at some stage the child will want their own space - then what do you do ? at the same time it seems insane to try to buy a bigger house and pay a lot more money just for the helper to have a room ? what do people do in reality ?? thanks !!