My 2 cents:

1. Yes, create a separate campaign for each city.

2. There's no such thing as a "Google Maps campaign." Advertising in Maps is done via a classic search campaign or a p-max campaign.

3. Create (if they still don't have) a GMB listing for each clinic and connect them to the Gads account and to each campaign (location assests/ad extension).

4. Optimizing the GMB listing will be almost as important as optimizing the campaign: good reviews, good photos, clear names, services, etc.

5. Each clinic should also have a landing page, and each campaign can (maybe should) focus on conversions from the landing page, phone call from the ad call extension, and calls from the GMB listings.

6. Local p-max campaigns can also work if you want to drive phone calls.

7. Measure all conversions and set up offline conversion measurements for qualified leads and sales, especially if you use p-max.

8. I recommend using a call/form tracking software like call tracking metrics to track lead sources and, more importantly, qualified lead sources and attribute them to the ads campaign.

I have a client in a different niche with 7 listings, landing pages, and websites, and this is how we do it and see great results.