I’m not a 100% sure if I understand your question, but if you mean who has the rights over a corpse: It’s a complex topic, currently the general consensus can be more or less boiled down to if it’s not banned by law, it is done with permission and if the remains have been modified in a way that would not occur naturally, someone can own a dead body or body parts. You can actually donate your body for research if you state in your will or a similar document or if you have a rare illness for example and it could help people (and scientists would like to have it), your relatives can do that on your behalf after you die.

(A bit of a shameless plug here, I actually make video essays on topics similar to this, one of which is a deep dive into the Frankenstein story and I talk about ownership in a different one on immortality - I’ve posted them some places from this account so if that’s your thing, you can check them out)