The City of Toronto recently released pre-approved designs by LGA Architectural Partners for multiplex buildings that can be built in low-density neighbourhoods: https://www.toronto.ca/services-payments/building-construction/building-permit/before-you-apply-for-a-building-permit/pre-approved-building-plans/pre-approved-multiplex-building-plans/

The designs are pretty cool, they also include one wheelchair-accessible unit per building (with space provided for a lift from the street level), including necessary clearance dimensions.

Eyeballing the dimensions and setbacks, the "narrow" fourplex needs a ~25 ft wide lot (~8 m), the "narrow" sixplex needs 28 ft, and the "wide" sixplex needs ~35 ft (~10 m). 25 ft is fairly wide in old parts of the city, but easily doable in inner suburbs, parts of which are fairly transit-accessible.

It's also neat that the plans are available for download and you can look at the design involved and learn how stuff is built in new low-rise residential buildings. Look at layout of utility ducts (elegantly kept mostly clear of main living areas) and plans for HVAC (including energy-recovery ventilation, which I think is now mandatory). The plans also have all-electric versions with no gas appliances, which I would think would be a no-brainer for new construction, but I dunno.

The narrow sixplexes have a cool layout of big 'penthouse' units, with the bedrooms on penultimate floor and living/kitchen areas on the top floor. That gets more light in, and terraces where they are useful. The wide sixplexes have more bedrooms, but the layouts feel a little clunkier to me.