If the product you've purchased or plan to purchase comes with care instructions, please follow those recommendations. If the item doesn't come with specific care instructions, you can follow the general rules of care. We found two articles that are helpful.
Outdoor cushions & pillows:
https://www.bhg.com/home-improvement/porch/outdoor-rooms/how-to-clean-outdoor-cushions/
Outdoor furniture:
https://www.marthastewart.com/8302510/how-to-clean-care-for-outdoor-furniture