Because of privacy reasons, we don't display freelancers' full name publicly on their Upwork profile. You'll be able to see their first name and last name initial when searching. Additionally, whether or not the freelancer's full name is searchable via search engines will depend on that specific freelancer's profile settings.
If you are in touch with the freelancer you're looking for, you can ask them to share their profile link with you so you can access their profile directly.
re: "Can someone please tell me how It would be or possible to search for a developer by name?"
If you are in contact with a developer, you do not need to search Upwork using his name. Just ask the developer to send you the URL for his profile page.