Sony XZ3 can't customize ringtones.

It seems that SMS ringtones can't be customized.

Taking a selfie depends on how you understand it.

508 doesn't have a selfie mirror and can't rotate the screen. Strictly speaking, you can't take selfies if you can see yourself.

But I always use the external screen as a selfie mirror. In good light, you can basically see your face clearly.

Or look in the mirror. You can also see yourself on the screen.