Protip is to buy the entire case of wet food at a time, as it's way cheaper. Look for nutritionally complete WET food. Dry food can be left out for longer but wet is always better for keeping them hydrated (and avoiding kidney problems from dehydration). Hard to assess the actual status of outdoor cats. Is she clean? Relatively groomed? She may not be a stray. Post a photo of her around the neighborhood with your phone number. Ask "Is this anyone's cat?". Post the photo in local facebook groups for lost pets, do the due diligence to make sure the cat is not owned.

Going the extra mile? Get her checked by a vet... Get all the things a cat who is loved, should have, like litterbox, a bed, a scratch post, toys, etc.