It depends. I know a couple who hired an architect who completely missed the need for added support for a one-story home where a wall was removed, and it ended up costing $5K extra they hadn't anticipated deep into the middle of their renovation. This couple had skipped going with a more expensive contractor who would have probably done a great job with more information about moving the wall up front, and it ended up probably costing them more overall to try to skip the more skilled contractor and rely instead upon the architect's advice for the renovation as a whole due to many problems encountered. The most important thing is that you get someone who is qualified for the job you want. Just because attic space is above won't mean the wall isn't load-bearing or won't need replacement ceiling beams to support your structure. Beware the cost of this as well, usually not inexpensive especially if you add in plumbing or electrical that must be moved. An experienced contractor would probably know what to do if just one wall is being moved.

I’d also ask - do I need to hire a designer? What will the furniture / flow ramifications be after this wall is removed?

Anytime you deal with an exterior wall which BTW is that wall you need to get real help in understandign what is involved and IMO the best person for that is a structural engineer , they will tellwhat needs to done to do what you want. Then a good contractor to do the work. I am wondering what the reason is for that removal.

I agree with Patricia Colwell. Either consult with a structural engineer or a general contractor who has access to a structural engineer. They should be able to tell you if moving the wall is even possible and what it will entail. A general contractor should be able to give you a ballpark estimate of what it would cost. If that's the only thing you are doing I would forgo hiring an architect unless you need the kitchen reconfigured because of the move. Good luck!

You will need the advice of a structural engineer and a good contractor. Keep in mind that garage walls that separate the garage from living space are usually fire rated and air tight, so their construction will be different from your regular interior walls.