I don't think 3-D printing is all that you need anyway. You want to build an entire model: create the shapes with their details and such, then put it all needed details, then paint it, add external details including signs and surrounding landscaping, etc. 3-D printing would give you a few of the correct shapes, but you could get those by cutting some blocks of wood and shaping some plastic pretty - not easily perhaps, but probalby with much less effort than doing 3-D printing.
I looked at photos of the Denver (top left) and the old Tulsa (top right) Casa Bonita locations online and assume you want Denver's (which I had been to, BTW), which is a more intricate model to build, but even the Tulsa one would require
expert model rendering in 3-D software because there is a lot of "gingerbread" to get right which would require very expert modeling however you did it. You would have to learn to use such software, well - I assure you that your or even someone experienced would probably make mistakes and need to fine-tune the model by printing it a few times and seeing where you didn't get it right, and then find a good, high-resolution 3-D printer that can print it it a solid enough material with fine enough grain to bo on your layout.
Specifically: you could go to the free site tindercad, and learn to use it (there are online courses), and one you learn, produce the required model file, and then go to any of more than a dozen 3-D printing companies, such as Shapeways, and load the file up to them and pay them to produce o produce the model. It would probably cost $100 to $300 in N scale depending on how fine a print matrix you want and what material you use and just how big the restaurant is. And realize that your modeling would have to be perfect:
you pay for mistakes (as you do, in a real way, in material cost, and time if you have your own printer): they send you whatever comes out, mistakes and all. BTW, if you wanted, once you had your 3-D model file correct, there are companies that would not just 3-D print that model for you, but if you requested, CNC machine it out of stainless steel or aluminum or any of dozens of other materials if you were willing to pay enough.
Frankly, I think the old fashioned way would be easier, for you or to find someone to pay. The buildings you want, are just blocks which you could make of wood, and the add the filigree and such as attachments, etc. You can buy supplies for "architectual modeling" - sheets of plastic and rods and such from Evergreen and Plastruct companies as used by the modelmakers architects have make models of buildings they have proposed to build, and make your own or hire one of them to do that. I built the restaurant in the low part of the attached, which I wanted on my layout. It is O-Gauge semi-scale model of Dino's Lodge, the restaurant owned by actor/singer Dean Martin in Hollywood that was made famous be being next to the detective agency in the TV show 77 Sunset Strip (1958-1964).
What you are asking for is for someone to build the entire model.