Estimates Vs Value

Having had just a few months of working in a Scrum team for Software development, I am seeking some thoughts on the aspects that make up "Value Optimization" for the stakeholders.

Is optimization of value also a function of estimates made by the Development Team?

In my opinion, estimates are not directly proportional to value but estimates can help you plan how much work (PBIs) you can convert into value.

Some considerations for value optimization could be through ordering of the backlog i.e. what do we need to convert to an increment to realize value?, PBIs that may be associated with High Risk, Competitive advantage, ROI etc.

How does the Product Owner take into consideration the Development estimates to re-order the Product Backlog Items that he/she considered to be of high value ahead of Product Refinement Meeting? 

Re-ordering work on the Product Backlog is a refinement activity. If the PO does this ahead of a refinement meeting, it suggests that some refinement is being performed without the Development Team being present.

Is optimization of value also a function of estimates made by the Development Team?

The purpose of estimation is for a Development Team to get their arms around how much work they think they can take on. If the flow of value delivery is to be optimized  a Product Owner may take estimates into account, along with dependencies and other insights provided by the Development Team.

Thank you @Steve and @Ian for the perspective.