Attachment is available for any outfit that has accessories like Buttons, Zippers, Buckle, Hooks, Sole etc. Not all outfits has attachment.
All possible Attachments are; Fasten, Gem, Hook, Buckle, and Sole and they all have similar properties; Color and Surface.
Color: Change the attachment color.
Surface: This is responsible for the Surface Properties of the attachment. There are 10 properties in total; Matte, Silk, Shiny, Metal, Glossy 01, Glossy 02, PVC, Matte 02, Velvet, and Satin. Each one is the combination of Metallic, Specular, Specular Tint, and Roughness at different values to give desired result.
To change influence: Outfit ‣ Properties Editor ‣ Object Data Properties ‣ Color Attributes ‣ Attachment Name