My parents have been filling in their LPAs, which are inherently useful and mean that it's clearly set out what they want done in case of serious illness. In their case, they don't want anything at all.
https://www.gov.uk/power-of-attorney/make-lasting-power
But why on earth is it such a ball ache and why on earth does it cost £92??
If my grandmother had filled one of these out, it would have saved the NHS literally hundreds of thousands of pounds for an utterly joyless extra month in her nineties that she didn't want.
But these forms are complicated (they're on it and organised, but have struggled) and not everyone has £92 lying around! Why aren't they readily available (and you could just be referred by eg your GP if it was something you were interested in?). It's crazy! I totally understand that not everyone would want one (and that's obviously fine), but if you are, it should be straightforward and free.