Are there filters to make more flattering selfies?

There are lots of third party apps designed to make you look better in a selfie. I've used FaceTune but there are lots of others available in the App Store.

Unless you're under twenty-five with perfect skin or have professionally applied make up, you're probably not going to look great in a selfie. No one looks that good when a camera is that close to their face.

I think it's something you'd need to experiment with. Read the reviews for the apps before downloading them. "Asian" has a big range of skin tones (and freckles) so, it's probably going to depend on your particular coloring. I have very pale skin with freckles and a pink undertone. FaceTune worked well enough. It was good enough at smoothing out wrinkles and discolorations.