The person who created the IP usually owns it, although that’s not always the case.
For example:
If intellectual property is created by an employee as part of their job and they have an Employment Agreement in place, the IP is presumed to be owned by the employer.
If IP rights have been registered, the person or entity named on the register owns those rights. They are the only party with the right to transfer ownership.
Let’s say a contractor or freelancer creates a logo or design for your business. They automatically own the copyright unless they (the assignor) specifically transfer it to you (the assignee). When the IP is assigned to you, you own it and you get to decide who can use it, how and when.
IP Assignment doesn’t have to be via a standalone IP Assignment Agreement, it could be covered in the Consultancy Agreement a freelancer signs with you.