Change resolution of depth/pcl/color of a camera in isaac sim standalone app

Hi all,
I am using an RGBD camera following the standalone example “standalone_examples/api/omni.isaac.ros2_bridge/camera_periodic.py”, the created viewport has an index 1.

The difference is that I’m not creating the camera as they do in the scripts but using:

from omni.isaac.sensor import Camera
         self.camera_ = Camera(prim_path=prim_path_in,
                                frequency=20,
                                resolution=(256, 256))

The camera works, but I cannot change the resolution for both RGB and the point cloud generated from the depth.
If I change the resolution argument in the Camera() class, it is ignored.
I even noticed that if I completely comment out the camera creation, it is still created by the omnigraph.
Is there a way to change the frequency it?
Do I have to create a camera, or does the omnigraph take care of it?
Is it possible to use cameras in combination with ros2 without generating a viewport?
Thanks