What is the minimum camera requirements to create professional quality videos?
The camera only plays a part in what makes a good, clean image. The most important parts are Lighting, Lenses and Knowledge of the person operating the camera.
If you film in a dark location and have to crank up the iso, you will get noisy images even with a 20k$ camera. If you have proper lighting and use a low iso, a 1k$ camera can look really clean.
I understand that you are looking for DOPs to work for you. If their reel leaves a good impression, ask then which camera they used and what gear they would recommend to shoot your project. Many social-media clips are shot with cameras such as the Sony FS7 or even the Pocket Cinema Camera in some cases. These are relatively affordable cameras (compared to feature-film equipment) and are certainly capable of creating images such as the ones you posted.
Don't be cheap on lenses as well. A 20k$ camera will look worse with a 50$ lens, compared to a 2k$ camera with a 750$ lens.
Usually, it's the DOPs job to recommend and pick out the equipment they use. If they insist on 20k$ worth of gear and claim that a slick production is impossible otherwise, maybe look around some more. However, do listen to their reasons when they recommend expensive gear as it might actually be reasonable and in your favour.