The Service Design Network has a section where you can share your own case studies. This is maybe the one specific site for service designers to post their work.

Obviously, outside of this platform, the usual players that are true for many professions are also true for service designers:

Behance is a popular platform for designers of all disciplines, including service designers, to share their work and connect with other professionals in the industry. It is a portfolio website owned by Adobe and is a great place to showcase your work and attract new clients.

Dribbble is another option for service designers to share their work and get feedback from other designers.

Both platforms are widely used by designers and have a large audience.

Check out all the questions about all the details on how to build a Service Design portfolio here.