Most consumer cameras do not let you run a script that changes exposure settings mid-exposure. A practical workaround is tethered shooting: connect the camera to a computer and use the maker’s control software or command-line tools to script setup and triggering. One example mentioned is Pentax with the Linux tool pktriggercord, which can script camera control before taking shots.

Focus is the harder part. Camera tethering may be able to trigger autofocus, but it generally cannot physically turn a manual-focus ring during an exposure. For true focus changes during the shot, you would likely need external hardware such as a motorized/servo focus rig like those used in stop-motion or motion-control setups.

So, in practice: exposure changes during a single shot are usually not supported directly on consumer cameras, tethering may help with automation around the shot, and motorized lens control is the likely solution if focus must change during the exposure.