Is there any 9v power supply to connect multiple tapo cameras?
The only reasonable way is to supply the cameras with one let`s say a 10Amp (10cameras) 12VDC power source.
Yoy can cable it in star or bus (or both) and convert it to 9VDC just before the camera.
To convert it to 9V just buy from Amazon a DC/DC Down step converter for each camera.
The converter is very small and you can put it into a small waterproof junction box just beside the camera, and cut a
short cord from the original power source to take the 9V from the junction box to the camera.
This way you have the mains and the power source where ever you want, and you take only 12 volts to the field/cameras.
This way the cameras are also isolated from each other.
One example of converter:
https://www.amazon.com/Magnolian-Efficiency-Converter-Supply-Waterproof/dp/B00A71E52G?th=1
This converter gives the camera stable voltage and enough current, and that`s all the camera needs.