A common document executed in the estate planning process is a Power of Attorney document. That document confers authority to another person, or persons, to act on your behalf either because you are unable or just want that person to handle certain matters for you. For example, you are in a car accident and can't handle payment of your bills, cash checks, etc., someone can handle those affairs for you. That person's title is the "attorney-in-fact" even though they are not typically an actual attorney in the ordinary sense. You can limit the authority of what the attorney in fact may do, or you can give them broad general powers to do generally anything necessary.
There is a also a Medical Power of Attorney in which you appoint someone to handle your medical and personal decisions, such as what medical treatment you receive or what facility you are placed at. This power only comes into play if you are unable to communicate your wishes.
These aren't required documents to have, but they are strongly recommended. If you don't have such documents in place, there are alternate ways to address these issues, but none are simpler and potentially could become divisive in certain family situations.