If you become incapable of looking after your own affairs you are probably too late to sign one. At the end of the day you need to trust implicitly the person(S) to whom you grant it.
Don’t pay a solicitor for this. It is easy to do direct on line. I have both financial and health POAs for my mother and My step dad. Just as well as he now has dementia and I am having shitloads to deal with (Finding care and selling his assets to raise funding) that no one else in the family...