What is the existing roof design? Flat, truss, rafter? Which walls are load bearing? What is the foundation? Guessing this is an old bungalow or north park type home.

You might get lucky and have a home with rafters peaking at the center crown. I could see vaulting ceiling here easily. Essentially you would be creating a truss. Otherwise you are into quite a substantial construction project as this is structural. Either way, you need an architect signed plans and calculations.

Have a general contractor stop by for a quick look. This is best as you may be relocating electric, water, or gas runs too.

Next best would be to take photo of exterior and submit a contractors forum. It will get you in the ballpark.