All individuals are required to wear masks/face coverings when at a business, both indoors or outdoors, whether employee or customer. Businesses are required to enforce this, so if a restaurant asks you to keep your mask on while you are waiting for your food to arrive, or after you have finished your meal, please comply.

You can remove your mask to address basic biological necessities like eating and drinking, but you should replace your mask as soon as possible if you have to remove it. This is especially important if you are eating or drinking in public areas -- indoors or outdoors. Wash your hands or use hand sanitizer both before and after handling your face covering.

(source: Marin Public Health Order)