How to update a param defined in the SDF file?

Question

I have a simulation with Gazebo-Garden and ros2-Humble to manage drones with a camera. In the camera sensor SDF part I have:

<sensor name="camera" type="camera">
  <camera>
  [...]
  <always_on>1</always_on>
</sensor>

This makes all camera started at the begining. I'd like to know if it is possible to set it to false in the SDF and then on user demand activate this camera.

I read to use service set_entity_state but it is not in my ros2 service list (and I wonder if it is a solution for gazebo-classic).

For info:

$ ros2 service list
/flotte/describe_parameters
/flotte/get_parameter_types
/flotte/get_parameters
/flotte/list_parameters
/flotte/set_parameters
/flotte/set_parameters_atomically
/ros_gz_bridge/describe_parameters
/ros_gz_bridge/get_parameter_types
/ros_gz_bridge/get_parameters
/ros_gz_bridge/list_parameters
/ros_gz_bridge/set_parameters
/ros_gz_bridge/set_parameters_atomically

I'm on Ubuntu 22.04