We have several of these structures in our neighborhood - the best ones have likely been designed by an architect as they thoughtfully match the style of the primary home (roof structure, windows etc) - but you may also be able to find plans online by searching "cape cod style garage"

(**edit: just realized you want to access the top portion of the garage from the upstairs in the home - so you want to build an addition to your home that includes a 2 car garage? That would likely need an architect who is skilled with older homes and enjoys those types of projects (not everyone does) - we had several contractors pass on our addition/renovation project bc blending new with old is a PITA)

I would be very afraid that the garage with what you want would overpower that house. You need an architect for sure and why access to a living space so maybe explain what the living space will be. IMO your house has too many roof angles and what ever you add will be both complicated to design well and very expensive . Get an architect , make sure you can do this in the property you have since sq footage is an issue on most city properties

The garage height would be around the same as the house. Plenty of room to add.