Focus peaking with your Sony DSC-RX100M2 or RX100M3 is a very useful feature when you want to focus your camera manually, but it can give you a false reading because it shows you what’s sharp on the viewfinder screen, not what’s sharp in the actual photo. With the screen being a much lower resolution than the actual camera sensor, areas that are highlighted as being sharp in the viewfinder can be pretty far out out of focus in the image you actually get.
To limit this issue, make sure you turn on your camera’s “focus assist” mode so that you can see a magnified view when you focus on your subject. Doing this will highlight only the areas that are sharp in the magnified view, which will give you a much more dialed in look at what’s truly in focus and what is not.