With dynamic resolution, render targets have the DynamicallyScalable flag. You can set this to state whether Unity should scale this render texture as part of the dynamic resolution process or not. Cameras also have the allowDynamicResolution flag, which you can use to set up dynamic resolution so that there is no need to override the render target if you just want to apply dynamic resolution to a less complex Scene.
When you enable Allow Dynamic Resolution on the Camera, Unity scales all of that Camera’s targets.