Per-Camera Resolution replaces Blender's single, globally-defined scene resolution with a resolution set on each individual camera. Whenever you switch cameras, either manually or through timeline markers, the scene resolution updates to the active camera's. The per-camera settings live in the Object Data properties, under the Camera panel.
Because Blender doesn't support animating the resolution by default, and a regular animation render only uses the resolution at render start, the add-on adds a Render Animated Resolution operator that works around this. Starting a render this way locks the interface until the render completes or Blender is killed. The add-on also lets you bake render borders: set a render border inside the camera view with Ctrl + B, click Bake Render Border in the Custom Resolution panel, and a new camera is created using the exact area defined by the border, which allows selecting multiple cropped areas in a camera.
It's available in English, French, and simplified Chinese, requires no special permissions, and runs on Blender 4.2 LTS and newer. Note that the animation workaround can sometimes cause stability issues; if you hit them, try disabling the add-on.