Being helpful and being permanently responsible for other adults are two very different things.

The difficulty is that families quickly become accustomed to roles. If you've spent years being the person who sorts everything out, everyone else may now see asking you as the obvious first step. You may even have unintentionally helped establish that arrangement by always saying yes.

That doesn't mean you have to continue doing it.

Start with the things people can reasonably do themselves. Instead of taking over, tell them how they can sort it out. If someone asks you to make an appointment they are capable of making, give them the number rather than making the call.

You don't need a dramatic announcement that you're no longer helping anybody. Just stop automatically accepting every problem as yours.

There will probably be some resistance because you're changing an arrangement that has been convenient for everybody else. That doesn't make the boundary unreasonable.