Depends on the cartographer. I take on a lot of very rough beginnings where my clients ask me to fill in details, make up names, terrain, and otherwise populate the surroundings for their stories. Generally settings where they've put a lot of thought into one or two key locations featured in a story to this point, so they have a few anchoring themes and ideas.
There are some cartographers here I would point to before myself if "geography expert" is what you want. They are high end professionals whose services don't come cheap, because they're not just making **** up, but doing a lot of complex foundational work to make a world that functions. They're the "hard science fiction" of cartographers. Namia and Azelor both come to mind, but I'm sure they're not the only intense world functionality nerds.
Speaking for myself, I specialize in being a creative fount. I'm good at making up a ton of stuff for people to play with, churning out fantasy building blocks and creative prompts based in the world. If you just want a pile of pretty bonus details made up to fill in the gaps and inspire you rather than a scientifically viable world, I'm down. Some of my favorite art has been a result of clients asking me to just make stuff up around their themes. I would appreciate a later January start though, because such a creation ideally involves preemptive brainstorming of a slightly greater level than a map that starts with a detailed sketch. There would be at least a few emails back and forth about what inspires you and the world besides just "Greek and Italy" since my goal is to capture and distill the essence of your world and your writing into a visual piece.
I have a few pieces in my portfolio that I think demonstrate what happens when someone really collaborates with me and lets me do what I do best.
A black and white map for a novel. Dralderth: the Dragon Realms. This one was made to go into a book, as if drawn by someone in the universe. This map was commissioned for $150 USD.
The Perilim, a black and white map for a DnD 5e campaign, this was a reward for the players for a quest completion, and drawn in character as a person in universe again. This map was commissioned for $220 USD. Both of these pieces were smaller print sizes for non-professionals and you would expect a similar quote for a black and white map at a screen resolution or smaller print size, my rates for black and white maps haven't shifted for a while as they take me quite a predictable amount of time.
If you're hoping for a master geographer, though, I would call myself more of a creative cartography illustrator than someone with a deep scientific knowledge of the geography of the world. I'm not sure which direction you're angling with for "geographic control". I might be able to help you, I might not. Cheers.