Rotating the camera by 90 degrees, not objects in scene

In my project there are a lot of objects in the scene so I’d rather rotate the camera than the objects. How can I do that? I use an OrthographicCamera, which means I work on 2D.

Current camera position (example left)

const camera =  new OrthographicCamera(0, width, 0, height, 0, 20);
camera.position.set(x, y, 1);

On the right is what I would like to achieve…

When I use camera.rotation.z = Math.PI * 0.5; Objects disappear behind viewport because my camera is set to the top left corner. Unfortunately, the camera settings is due to the coordinates it gets from BE.

Seems to be solved at stackoverflow: