How do I expose milestones in the SR layout?

You can modify the service request layout to show the milestones as a part of the service request details.

Fields shown at the service request level represent the next milestone due for the service request. Note: The time remaining field is an approximation and it's rounded down so that agents don't think they have more time than they actually do. To expose current milestone fields on the service request layout, create a user-defined layout in Application Composer, and add the MilestoneID field to the Service Request Summary page.