Yes, you can traditionally publish without an agent, but it is generally much more difficult to do so. Most publishers will not even consider a manuscript unless it is submitted through an agent, and those that do usually only consider submissions from well-known or established authors. Additionally, most agents will not take on a new author without a manuscript that has already been accepted by a publisher. So unless you have some connections in the publishing industry or are a particularly good self-promoter, it is generally advisable to find an agent before trying to traditionally publish your work.