It all depends on the architect. Frank Lloyd Wright, for example, did everything outside, inside and garden. You need to find an architect who is experienced in all of these things. They do exist.

PS: And you must be willing to pay for all of these things!

Good luck on your project.

As was said, it depends. For my build I first chose my architect, after receiving plans, I interviewed contractors and interior designers. One architect wanted to design and buy all the interior finishes, good for some, he was too controlling for me, so I didn't use him. After getting bids I hired both the contractor and designer. I hired an interior designer to coordinate all the interior finishes. My architect did not plan the kitchen with much detail, that was fine for the designer and contractor. Each of them suggested changes to the plan that I liked. My last build, my architect was available during construction for oversight and consultation, my architect died before we began, so that is not an option. It is up to you how much you want each one to do and what each one is willing to do. You do need to plan all your appliances and fixtures soon and make adjustments early. Also you need to plan for the rough plumbing early. I hired a designer because decisions come fast and early and the finished product looks nicer. Sometimes there is animosity or competition between the parties, my contractor and designer have worked together on several jobs so I know they get along and compliment each other.

An architect would do all of those tasks unless you wanted someone else to do them like an interior designer or kitchen designer, etc. but that work should be coordinated with the architect.

There aren't many architects on the forum so I doubt you saw many instances of them deferring to builders regarding design issues but it might be appropriate to ask a builder for something regarding the means and methods of construction or when an owner is trying to figure out something that would only be known to the builder like why a builder did something they didn't understand.

It is common for GW owners to ask other members to guess about the motives or intentions of a builder when it would be more appropriate for them to ask the builder.

Our architect did a complete plan with kitchen, built ins, electrical plan, exterior hardscape. We asked for help with finishes but this was less successful. We did work with some basic ideas from him so in the end we did not stray too far from the original concept...but we needed to rein in expenses.

One architect we interviewed would not work without an interior designer on the team. He did mostly (very) high end, and our home would have been his rock bottom project, so we passed on him.

Just realize that the more architectural and designer input you have, your costs rise expotentially!!!

As largely a spec builder outside the USA, I am fortunate to have access to the services of architectural technologists for the building plans. I always have these checked by a structural engineer; and, indeed, engineers are the pros I most often consult with a few more times during a build.

I'm comfortable with my own design choices--except that when I depart from "builder" white, grey or beige, I pay for a colour consultant/designer. (Most homeowners should, too, from what I've seen.) Kitchen and cabinet design I leave to accredited pros in the field.

Whatever pros you choose, it's essential that they be constantly aware of what the other is doing and hopefully that they interact in a professional manner.

When I've done a custom build it was so much smoother to deal with a designer who understood the building process and how little changes were big changes than with their clueless but entitled clients!