The team who are going to do the work are the ones who should estimate the story. It makes no sense for estimates to be made by anyone else because people outside the team simply have no idea how the team are going to get it done.
Typically in Scrum, the team is a scrum master, a product owner and several developers. The product owner is part of the discussion on estimate, but for setting estimates, it's mainly so the developers can explain why they are setting an estimate differently to what the PO guesses. They're the ones who are going to do the work, so they're the only people who can size it.
Hi @Monika Rawat , welcome to the community.
I don't quite understand your question. But let me offer some information that may answer your question.
Story point estimation is done using the Story Point field. You can restrict who can update that field if that is your goal.
for what it's worth, in all cases where I have work the developer is providing the story point estimate. It is hard to imagine that a product owner would be able to effectively do that but anything is possible.