Can I restrict projects to certain members?

You can restrict the projects to certain members when creating new projects in workspace page. By default, the person who creates the workspace is the administrator of the workspace. As in projects, a workspace can have more than one administrator. workspace administrator can decide who can access projects and see billable rates. You can decide the type of the project upon creating it.

Public projects can be created and edited only by workspace administrators. Private projects can be created by all team members if the workspace settings allow this. You can change the project privacy settings from the project edit page.