What can you feed kittens that are 2 days old?

By far the best food for tiny kittens is their mother's milk. They need nothing else.

If for some reason the mother isn't present, you must either quickly find another nursing female cat who can take on more kittens (your local animal shelter may have some), or buy some KMR (Kitten Milk Replacer) from your vet. Your vet will be able to show you how to bottle feed kittens. Such tiny kittens will need to be fed at least every hour around the clock, and will also need to be stimulated to produce waste after every feed.