The following drinks are GF and free from cross-contact as-is: plain iced, hot, or cold brew coffees, Iced chai lattes and regular espresso
When ordering during busy times at Starbucks, ask for your drink to be made in your cup to prevent cross-contact.
Ask them to wash the blender before preparing your drink to prevent cross-contact with gluten.
Ask them to wash the shaker to prevent cross-contact.
When ordering drinks with cold foam, ask them to wash the blender again, because not everything made in the blender is gluten-free.
Where I share more tips on how to order gluten-free drinks.