The most important thing the federal government could do insofar as it controls the building codes, or at least the model code process that eventually filters down, is slim down what are called the vertical circulation requirements. These are the elevator requirements and stair requirements. Obviously, you don't want to sacrifice safety, but you need to find the right balance. The more vertical circulation you require, the larger the building has to be. Strangely, generally, the smaller the building, the easier it is to build family-sized apartments, so you want to make it easier to build small apartment buildings.
As I understand it, a number of cities and provinces are working on this. I think they should probably move a little more quickly and be a little more ambitious, and then there are also planning reforms that go along with it. I don't know the Canadian context well enough to know what role the federal government has there, but in general, you will find the most family-friendly apartments in any place in the lower density areas.
You don't want to limit housing to only very tall towers on very large sites. You want to open up some of these single-family neighbourhoods to modest apartment buildings of three to six storeys. That's where, for a number of reasons, it's always going to be easier to build family-sized apartments.