Making it codified as a right is a little difficult because the amount of risk each person can take without risking something MAJOR like death is different.
For the most part though, the major stuff already is a right. You have to have the right to refuse medical care and medicine taken from you by the courts after you've proven you can't handle them starting in teenage years. Same with finances, all adults can open a bank account, sign contracts, or apply for a credit card unless they lost it through the courts. Most people can marry and divorce within the month and spend all their life savings on corgi puppies if they really wanted to.
Where it starts getting sticky is when things like sex, eating healthy, things like that come into play. Most old people in care homes, even with dementia, can consent to sex with another elder in a care home. They know what no means, they can handle some drama. It's a common place thing for families to try and stop it because "grandma doesn't know what's going on" even though she knows Harold down the hall lost his wife 20 years ago but still takes out his false teeth for the ladies if you ask him nicely and she's been asking for a WHILE. Care homes won't stop this as long as they know grandma is asking and knows what she's asking for. Someone else might not be lucid enough to know what's happening or why and CAN'T consent, and those people are the ones who are safeguarded because they can't choose to take that risk on their own.
Institutions have something informal called the "Burrito Test" where you should be free to get up and microwave a frozen burrito if you want one, if you can't it's a bad institution. However, again it gets sticky if someone CAN'T make themselves a burrito or if they have something like Prader Willi (which makes you permanently starving level hungry and often intellectually disabled) where they need someone else to manage food intake for them. But it's still important to let people choose to take risks that are fairly safe for the individual and people helping should look for other ways they can support risk taking.
